Just a bug with the UWP. Bookmarks made thru the PC app don't appear in the mobile app. Maybe some lack of code in the mobile app perhaps? I hope you will fix this
Thank you for submitting an idea to Xodo’s UserVoice forum! This is more of a support request, and we would love it if you could contact us via xodo.com/support so we can help resolve this immediately.
The Xodo Team