I just updated to 6.3.1.228 and I'm seeing this:

Dear customer,
your backup plan Kamar Backup completed, please see below for more details.

Error
Files and folders were skipped: 42 (code: 1603)

I checked the log - it's correctly skipping specified folders, system and hidden files, so no error.

I ran the job again - same result.

I see from the discussion above that this should have been fixed in v6.3.1, but as you see - it's still there!