Masks Intermittently Disappear in AE

We are rotoscoping eye socket shapes for about 50 shots with relatively simple masks.

All the work is done but when we add feather or mask offset the entire mask disappears for 1 frame or more in AE Masks

They do not disappear when there is no feather nor offset.

It seems that it can fixed by deleting 1-5 points on the mask.

I believe it may be similar to the bug when random points shoot to infinity on the AE masks.

Any easy way to fix this?

Thank you,


Hi Chris,

So you’re only seeing this inside After Effects once you apply the AE mask feathering? That is most peculiar.

Are you tracking the eyes as well, or only doing manual roto?
How small do the shapes get?


It is peculiar. In fact it sometimes only happens with a specific feather/offset amount. So I need to check every frame after tweaking the feather/offset.

I have found a small workaround. I go to a bad frame, I move each point a little, often one point movement makes the mask comeback. So I delete that point and it works.

I can send you a file if you would like.

Thank you,


Hi Chris,

Yes, a file will help to see the problem. You can send here: martinb[at]

Hello Chris,

Did you find a solution to your problem? I’m having the same issue and even though tweaking the keyframes and moving them around sometimes solves it for a while it then ends up showing up on other random frames of the mask as well. Its starting to feel a bit madening.
You’re the first person I’m encountering that is describing the same issue.

Thank you,


Hi Maria,

The quickest way for us to help out is for you to send us the project and we can take a look. Same email as above will suit to check this out: martinb[at]

We should only need to see the project file, not the footage.

Can you describe your issue in further detail?


So there was no fix to this?
Cause im also having this issue, masking an eye, it disappears between 1 and 83 pixels of mask expansion.

Can you tell us more about the specific details @hsmiah00?

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The version of mocha is 6.0.1, its the one that comes with after effects.
I’m using a PC, (R5 1600, 16gb ram).
The problem I’m having is that after turning the mask into an ae mask, and then try to use the mask expansion tool, the layer appears invisible between 1 and 83 pixels.
What I did was track a mask in mocha of my eye, then turn that into an ae mask, I copied the mask to a black solid, then I went and increased the mask inflation to 2.
What I expected to happen was for the mask size to increase or ‘inflate’ as the name suggests so that the solid it was applied to would cover a slightly larger area.
What happened was that the layer appeared invisible after increasing the inflation and after fiddling with the slider I discovered it was between 1 and 83 pixels.
I haven’t tried any other versions of mocha or ae.
From attempting to recreate it, it seems to affect smaller masks more, sucha as only 20 odd pixels up or across, and the ranges of where the layer begins disappearing tends to change. It might also be an after effects problem not a mocha problem. Thanks for any help.

Ok, that version of Mocha AE is fairly old. The latest version is v7.5.0.
Can you show me an image of the feathering before and after in After Effects? This could just be related to the control point positions or a position issue in the spline keyframes.

I was just trying the Mocha 2020.5 and it is still an issue.

Im having the same issue! couldnt see here any solution! please help me!
EVERYTIME im trying to change the expansion of the mask the was created in Mocha
the content of the mask are gone!!

Any word from Boris on this issue? Im having the same problem. Specifically when you expand the mask. It will pop on and off with random values of expanding. I found a quick and dirty work around. I applied the masks from Mocha to a solid and precomped it moving all attributes. Use the Simple choker as the expander and fast blur to get the feather back. I then used that as a track matte for my footage. It seems to work. Not ideal though. For reference I am running AE 2020 17.1.1 on Catalina OS 10.5.4

This really sounds like it could be a bug we just haven’t seen on our machines, we will have to try to reproduce it.

Was there ever a fix for this? I seem to be having a very similar issue as well.

AE 18.2 – Mocha 7.5 build 1284
CPU: Intel i9 10900K
GFX: GTX 1080
64G DDR4

The Issue: After rotoscoping a small selection of a clip (I’m working on a series of clips, all similar and experiencing the same issue, btw) I use the plugin to export the AE mask. I set the mask to subtract. (My plan is to remove a small piece of paper from an actor’s face.) The mask subtracts correctly. However, when I try to “Expand” the mask via the expansion option weird things are occurring; The mask will randomly disappear or disable on random frames, inadvertently not subtracting anything. ie. the paper shows back up.

The mask is aligned properly still and keyframed in place. The issue is consistent in that it happens every time to every clip. (I have worked on about 4 out of 20 thus far.) The frames that it “drops” are random. On the previous 3 clips, I was able to keep it subtracting consistently by deleting a frame or 2 surrounding the “drop”. With this 4th clip, the workaround is not working.

Any advice would be greatly appreciated.

This is only happening with roto masks from the Mocha plugin, not an AE-originated mask.
The “drop” happens to random frames, not every frame.
I updated AE today in the hopes of a fix but the problem persists.
I checked that my GFX driver was up to date and it is. I reinstalled the driver just in case and the problem persists.
I have purged all media and cache files and the problem is still there.
The “mask drop” shows up on exports as well.

In Mocha, can you see if the surface tool is still on in the frames the mask is jumping on, or see if the edges of the mask in Mocha are folding in on themselves?

What codec are you using with your footage as well?

I will check with @martinb and see if this is an outstanding issue.

I wasn’t observing the surface tool during the rotoing process but when I click it on, it stays “on” the entire track. However, it does jump around quite a lot, with no apparent correlation to the random keyframes the mask stops working in AE.

My footage is DNX HQ in an .mxf container.

One workaround mentioned above does consistently work for me: deleting points on the mask within AE down to a smaller number. Can’t pinpoint any specific number. However, taking the expansion up higher will result in the issue popping up again.

Interesting, can you send the project file to me at MaryP at and CC MartinB at

We use proRes4444, dpx, and exr

I believe we have had the problem with all.

It sure would be cool if native AE masks without baked keyframes could be exported. That would allow for easier in AE tweaking and feathering.

That is on our wish list as well for sure.