Cogwork ring 2suffix cant be changed + scour stays rare

Hi, if a cogwork ring is supposed to behave like every other rare item, with the exception that its magic versions has +1 suffix and -1 prefix, if scoured with suffixes cant be changed and only 2 suffixes the item should become magic.

Please explain this behaviour, thanks

https://www.twitch.tv/videos/2512062993 3:09:19