I have over 100GB of music synced to my Samsung S9+ Android phone for offline use. I entered Offline Browsing mode, then after I went online, none of my synced music shows up. I can find it by searching, but can't browse. I've synced new music since I began having the issue and it hasn't helped.
I bought Plex Pass this past week just for the offline sync feature and I must say I'm very disappointed in the offline features. Sync performance has been abysmal, now this. :/