That seems to be a media storage bug. If you haven't already, please try doing a cache partition wipe in the recovery menu. I made a post on how to so this in "Tips".
If solution provided by @THE_GEEK_19 doesn’t help, please send us an error report with screenshots from One UI Beta App (Beta Feedback -> Send feedback-> Error Reports -> "Select Category" -> Input frequency and Description" -> Send (Top Right Icon). We appreciate your help for supporting beta program.
