After updating to 1.4b also found this glitch. The justify-content is not affecting anything in the backend. The setting does not pass to frontend CSS either. Can be only fixed by writing CSS manually.
I’ve already encountered this myself and added it to our bug tracker. Align items and justify content are currently applied to the ul instead of the li, which is wrong
I just came back to tell that i realized this bug was in my own brains. Then found your reply and I’m now uncertain about everything again
Anyways it seems that when i set align-items to start it’s doing what i was after in the first place. I was using justify content because of the visual presentation of the buttons.