Ambitus reacts wrongly on insert/delete measure

1. Create a new piano score.
2. Add some notes
3. Drop the Ambitus on the first measure treble clef.

Now, select the first measure and press INS to insert one measure. The ambitus will move to the next measure, from the first. It should stay put.

Now, follow the above instructions 1-3, but now delete the first measure (select and ctrl-delete). The ambitus will disappear as well. It shouldn't be deleted with the measure contents, just like the time sig doesn't disappear anymore when you delete the first measure.