I set up several full re-encodings that crashed (in the sense of just closing out, no crash handler popped up), trying x264 and lav AAC first, then several other combinations. Then I tried just loading the file and saving the project, absolutely no transformations or encoder saves -- crash. MP4, Mkv, etc all work fine.
I've attached the log, although I don't know how useful it is, since it ends at "Scripting muxer" which I already knew.
Win10 x64: 10.0.17763.475.amd64fre.rs5_release.180914-1434
OK, I found the .wer, without the dump. I can generate a dump if necessary. It does have this tidbit:
Sig[6].Name=Exception Offset
Sig[6].Value=PCH_84_FROM_libADM_coreUtils6+0x000000000000182B
Sig[7].Name=Exception Code
Sig[7].Value=c0000005
Can it be that you installed the VC++ release build into a non-empty directory where previously a MinGW-built Avidemux was installed? Both are not binary-compatible, which would explain the crash.
There is no MP4v2 muxer in VC++ builds. Additionally, it is planned to remove it completely as the MP4 muxer is now capable to move the moov atom to the beginning of the file on Windows as well, which is what "optimize for streaming" means (you would need a recent nightly to use this feature, however).