File permission troubles on High Sierra

I've come to find a problem since I upgraded to High Sierra. The last couple of days, as I was organizing some files and folders, some operations like copy and paste, or move, were denied by the OS, with no helpful info in the error dialog or the system log.

Even today, I was trying my hand re-encoding some home videos to HEVC, with QuickTime, and the last two failed. The error message said I didn't have permission to write to that folder (my home folder, so there shouldn't be a problem), but at least it got some useful info.

Repairing the volume in Disk Utility didn't solve the problem, nor restarting Finder. Yesterday I had to reboot the machine to get rid of the problem, and today was the same. The problem appears to be localized to the folders I'm currently working on. Yesterday, the locked folder wouldn't even display its contents, appearing as an empty.

My guess is some issue with read and write privileges on APFS, but I really don't know. Does anyone have experienced this issue? Is there anything that I could do to work around it until Apple fixes it (assuming they are aware of the problem)?

Thanks in advance.