I can share some information that can help you fix the connection between QuickBooks Online (QBO) and Wix, @69designs-bikeri.
To help you check what stopping the Wix app from syncing to QuickBooks Online (QBO), I suggest reaching out to their Customer Support team. They can isolate the issue you're having in a secure environment and help you resolve it. You can go to their website to check for their phone number.
For more information about integrating QuickBooks Online using QuickBooks Connector (OneSaas), refer to the following article: Integrate QuickBooks Online with Wix.
I'm always here if you need further help with your QuickBooks account. Just let me know by leaving a reply below. Keep safe and have a great rest of the day!