I have the same problem. Can't import from my Canon cameras using gthumb OR copy and paste in caja.
I left updating to Update pack 7 for a couple of months after it came out in the hope that any problems might have been sorted, but that's obviously not the case.
What a pity. I had such high hopes that LMDE would free me from the regular update syndrome which I used to have with Ubuntu, and after sitting through some 1300-odd updates, I really hoped that it would work.
Oh well. Luckily, I took the most important precaution of doing a full backup before updating (bless you, Redo Backup) and am back to where I was before. Time to look for a more reliable distro, I think.