Incorrect tempo after tempo edits in presence of fermata with time stretch enabled

There are several scenarios that are very likely to be related so I'll put them in one issue.

Scenario 1:
1) Open the attached score (it contains a tempo marking and some time-stretched fermatas).
2) Remove the tempo marking.
3) Play the score.
Result: playback tempo is 120BPM before the first fermata (correct), fermata plays time-stretched (correct), after the fermata tempo goes to 200BPM (wrong).

Scenario 2:
1) Open the attached score
2) Assign different tempo to the tempo marking (either via editing its text or directly via Inspector).
3) Play the score.
Result: time stretch of fermatas is ignored.

Not a regression, both issues can be reproduced at least since version 3.0.2 (and very likely in earlier versions too).