@Tore Omdahl - If you are unable to unlock objects that are already locked, this could be due to a new feature called protected lock which allows the object creator to stop others from unlocking the objects.

More info here:

https://community.miro.com/changelog-discussion-31/protected-lock-live-embed-and-more-mind-map-features-2281

However, if you unable to both lock or unlock objects, then I suspect that the board you are trying to do this on may not even belong to the team of which you are an admin/member of and that you could be viewing the board as a guest editor.

To check this board's location, open the board, click/tap on the board title, and check the Location field which will show the team name where it currently resides and a project it may be in:

@Robert Johnson - thank you for quick reply and guide!It did not help that the board owner chose “anyone can unlock”. But we tried another thing. I had the board owner invite me to the board once again with “can edit”. And suddenly I got permission to lock and unlock items. I am not sure why it did not work in the first place since I already had “can edit” permisson. Again, thanks for pointing me in the right directions!