Thank you for your post. I just have some questions so I can narrow down the issue.
1. What device OS are you running? iOS 13 or Android 9, etc.
2. What model is your device, i.e. iPhone 8 or Samsung Galaxy s9, etc.
3. What version is your Avenza Maps app?
Let me know and once I have a better idea I will be able to advise, additionally, can you send a screenshot of your My Maps tab to firstname.lastname@example.org?