Collapsing groups states are changed after the first group removing

Scenario 1:

1. Open "_common_data/scenarios/msa/ma.aln".
2. Click on the "Switch on/off collapsing" on the toolbar.
   Expected result: there are two collapsing groups one right after another: "Conocephalus_discolor" and "Mecopoda_elongata_Ishigaki_J".
3. Expand the "Conocephalus_discolor" group.
4. Remove the first group: select all sequences in the "Conocephalus_discolor" group and press the Delete key on the keyboard.
   Expected result: "Conocephalus_discolor" group is removed, "Mecopoda_elongata_Ishigaki_J" is still collapsed.
   Actual result: "Conocephalus_discolor" group is removed, "Mecopoda_elongata_Ishigaki_J" becomes expanded.

Scenario 2:

1. Open "_common_data/sanger/alignment.ugenedb".
2. Click "Show chromatograms" button on the toolbar.
3. Expand "SZYD_Cas9_CR51" row (the third).
   Expected result: all rows are collapsed except the third.
4. Click to the first row name.
5. Press Delete key on the keyboard.
   Expected result: the first row is removed. "SZYD_Cas9_CR51" row is expanded, all other rows are collapsed.
   Actual result: the first row is removed. "SZYD_Cas9_CR51" row is collapsed, all other rows except "SZYD_Cas9_CR52" are collapsed too. "SZYD_Cas9_CR52" row is expanded.