Editing repeated events does lose track of the exception days.
1. Create an event at the first day of the week which repeats for five dayhs
2. Drag the third day instance to a bit earlier time
3. Click on "Only this instance"
4. Drag the first instance of the repeating events to a bit later time.
5. Choose "All events in the series"
- At step 4, the earlier instance will stay unaffected
- At step 4, the four remaining instances will move to the new time
- At step 4, both the earlier instance stays unaffected the four remaining instances move to the new time. However, a new instance appears between the second and the third ones.