Please run the attached code and try to change the hours to 3.00 either using the arrow or the up key.
The QDateTimeEdit becomes empty and it logs:

QLineEdit::setSelection: Invalid start position (11)

Other issue:

1. set the hour to 4, (same date) lower the time to 3.
2. Now the "down" spinner gets disabled.

Result: it's not possible to jump from hour 3 to hour 1

Other issue:

1. set the date to 27/oct/2019
2. set the hour to 1
3. advance the hour

Result: hour 2 is only shown once (without any indicator for DST/standard
time)