Hi @Shanaliens
I think you may have found some issues there for sure. It sounds like you do have auto-refresh switched on, but might be worth double-checking. I did read somewhere that it can take TikTok up to seven days to fully refresh audiences, which seems a bit long but may indicate that they only update audiences once the size of your pixel audiences reaches certain milestones.
One other thing you might try is uploading customer lists and see if you get a decent match rate with them. There’ll always be problems there as its dependant on consistency in the data that people use across different platforms, but could be worth a try.
I hope some of that helps…