Iām having this exact issue using 1.36 and going local crypt to ACD. Seems I have to just restart and hope for the best. Happens with both copy and sync and mounted and unmounted. Canāt seem to find a rhyme or reason to it as its very sporadic. Files are around 7GB-10GB.
I also have stalling issues with copy and sync on Ubuntu and now also on Windows.
It looks to me as if very long paths and file names are part of the problem. After I deleted one example from local, it went through.