Hello Vincent,
It is a bit hard to know for sure what is wrong in your environment, but we can start with few tests:
- first of all, to be on the safe side, make a copy of the folder you started to encrypt, in case something goes wrong that we do not encounter data loss
- open console and see if there are some messages appearing all the time, which might be Espionage related
- do you have sufficient disk space to encrypt the folder you wanted to protect?
- all this does not make any clue, abort the encryption, restart your mac and create one test folder with a single file in it, and try to encrypt that one, see if that goes well, if it does, try again to encrypt the folder you tried now.
Let me know the outcome,
Rgds
Zsolt