Your original message has “…;/proc/;/proc/*;…” which is what Uroni was pointing out - it will back up the /proc/ directory but nothing within it…
When you remove the trailing asterisk so it is “;/proc/;*/proc/” (or just "/proc/”) then it won’t even try to dip into the folder…
EDIT: This is only using /proc/ as the example directory, you will want to retain other items in the exclusion list, but probably drop the * trailing the directories…