This is quite confusing behavior: say we have 3 tasks:
- 1 in group A
- 1 in group A and B
- 1 in group A and C
Then we do a query to show all tasks in group A: we get the 3 tasks. Now we ask to group the results by group: we only get 2 tasks:
- group B
- task in groub A and B
- group C
- task in groub A and C
The task that is only in group A is gone from the results: it should be a in fake group called "Others" or something. Hopefully this is easy to fix.