Moho-4K -> MP4
Win7 i5 64-bit: NOT OK
Win10 i5 64-bit: OK
I am sure this is due to limitations of the default Windows 7 codecs. For example: I cannot playback the 4K MP4 created on Win10 using WMP on Win7. But can play using VLC on Win7.
Exporting Moho-4K on Win7 to PNG / AVI is OK, and Adobe Premiere seems to like it.
I also tried creating 8K (Moho-8K -> PNG -> Premiere -> MP4) and it works, with playback on VLC.
Could not create Moho-8K -> MP4 on Win10 though. Same error as you have.
Moho 14.3 » Win 11 Pro 64GB » NVIDIA GTX 1080ti 11GB
Moho 14.3 » Mac mini 2012 8GB » macOS 10.15 Catalina
Tube: SimplSam