I just got Mocha Pro 2020.5 on my Windows 10 home computer with a GTX 1070. I tracked my rover to remove and when I try to create the clean plate I get the error seen in the attached image.
My 360 footage is Pro Res 422 stitched from Mistika VR. I updated my drivers and tried choosing several different drives to save the .tif all with the same error.
I just tried to save a clean plate tif file in Mocha Pro 2020.5 (from AE) and had no problems.
The conversion message makes me think it is related to color space which had a big update in 2020.5. Is your AE project set to float 8, 16 or float?
Also - in Mocha, under prefs, can you look at the new color pref panel and take a screen shot. Maybe try switching from OCIO to Legacy? Then restart AE and try again.
“Legacy” is the non-OCIO way of handling colour in the modules. All data is saved out at the same BPC as the source coming in.
The OCIO method is dependant on settings, but it appears 16 bit files are having an issue.
This appears to be a bug in the clean plate conversion. We have someone looking at it.