Hey, Hello - hope you are well.
This can be a frustration. It's a little bit of a strangled path sometimes. I wonder if you would try this for me. If you have already tried this then disregard.
In the android app
1. Click on the three lines top left
2. Scroll down and click on settings at the bottom
3. You should see a list of calendars (you may need to click on "show more")
4. Find a calendar that you are having problems viewing
5. Top right you will see a toggle for sync....I wonder perhaps if this is switched off?
Let me know how you get on :)
Neil