Recapping: most of the bugs I reported during 21.5 beta testing were fixed... BUT! (there is always a BUT!), still some bugs there, in this RC still see a "minor bug" related to GUI: the product does not save/keep the visual user custom settings changed, it re-sets them all to default in every system start or if You exit the product and re-execute it.
Example: if You change in Quarantine -> size columns, if You add new columns (and/or change their size), change size of that window, etc. in Intrusion Prevention -> Manage Applications, and this is also applied to other windows settings of the product... in previous versions of the product this was working fine, and user custom settings were saved.