I can help add some details about the missing bookmark in QBO App.
Reinstalling and repairing the QBO app will also remove the bookmarks. You may need to add the bookmarks again after resetting the app data.
If you continue getting this unusual behavior using the QBO App, I'd suggest reaching out to our Online Support so they can isolate the issue further using their tools. They can open an investigation for this if the issue persists.
Please let me know if you have other questions about your bookmark lists, or anything else, by commenting below. I'll be here to help however I can. Have a good one.