Text from the comment field of an event cannot be saved after it has been modified

Spotted with version 6.0.3 (elementary Updates).

I have created a new event.
Entered a comment text,
saved the event.
And then opened the event, deleted the comment text in different tests, as well as changed parts of the text and clicked again on save.
The event flashes - why is the animation flashing after saving? - and I open it again. And again the old original text is there in the comment field. By the way, I have observed the same thing with duplicated events.

My expectation would be that changes in the comment field can be saved permanently.