Form is not sent when admin is not owner of the page

[erru0000]

An editor has created a page and is owner of it.

I, as admin, create a powermail form on that page. When checking it out, it will not send from frontend. No error there, it just jumps to the beginning of the form with keeping the filled fields.
Even when I take a form which is working on another page within the same website and put it on this page, it will not send at all. All settings are the same as on the working page!

Once I change the ownership of this page from the editor to myself, the form is sent without any problems.

This is really weird and it took me some hours to figure it out.

TYPO3 12.4.26, powermail 12.5.1