Calender view click-and-drag time input in wrong date-time format

Just today the click-and-drag time input on the calendar view gives a wrong time-format (see printscreen): anybody idea's what recently has changed?

When I do an 'add new' in the all-items view I don't get this problem, but this click-and-drag feature is necessary for client and ease of use... 

So it seems something specific to the calendar-view? Something to to with the form-entry that is moving more to the PowerApps-system?