There was an error in the wording.
Please replace ‘Project’ with ‘Team’.

@Fumihito Oura - This is the result of a recent change by Miro which results in your Starred (and Recent) page only showing boards that are in teams that you are a member (or guest) of. And, unfortunately, the fact that you can still star these boards at all is confusing to users, so they will likely soon remove the ability to star a board that resides in a team that you are not a member of.

More of this change here:

https://community.miro.com/ask-the-community-45/can-not-find-recent-boards-17842

Title updated

...still there’s a glitch - after I removed all forced-created teams I were part of I could login and was forced newly to create a new team. suddenly it showed all my starred boards, but they went hidden after opening one. So I’m gonna delete my team again and try this until I see my personally starred boards and will move back to dumb browser favorites again… 

And it worked. After login you need to create a new team (which i did) and then after clicking X on the share-team page you see this page which shows your personal recent and starred boards.

So hurry up to get there before it gets “fixed” and save your personally starred boards into favorites.