iCalendar deleting text in new events -the event remains, but without text

Hi everybody,

After creating a new event in iCalendar, the text is deleted. Changing an event from its calendar to a different one can have the same effect. Ultimately, the event remains in the correct time slot, empty (no text).

The problem happens frequently, but not every time I create an event. The affected calendar is linked to Exchange.

Would you be able to help me with this issue?

iCalendar is running in a new Apple M4 Pro; macOS: Sequoia 15.4.