Sorry for the very late reply.
I've taken a look at this bug and I'm not able to reproduce it.
I've tested in linux, win7 and win10 (I don't have access to win11)
I know it exists but I haven't been able to fix it yet because of that.
In the meantime, when you export to character, can you try to write the filename + extension, instead of just filename (ie, 'char1.png', instead of 'char1'), as MadMedicSoft as sugested ?