Steps to reproduce:
0. Make sure you have at least two labels which can be added to issues before starting.
1. Go to an issue
2. Click on labels
3. Add a label (any) by writing its name and pressing "Enter"
4. The goal is now to exit the label section, saving the changes. If you press "Enter", it will add another label (whichever is on the top of the suggestion list). If you press "Esc", it will exit the label section WITHOUT saving the changes. The only way to save is by pressing the "Save" button, but that is hidden under the dropdown, and tabbing once does NOT close the suggestion list.

See also the attached screen recordings demonstrating this.

Workaround:
Press TAB (selects checkmark hidden behind dropdown), then ENTER to accept.

If you want to see the hidden checkmark / cross controls, move label menu close to the lower end of the screen, so that the value dropdown is drawn above the label field.