Bugs (multiple) - during a traditional draft in FF

I experienced multiple bugs, frustratingly enough, they happened in the same game:

I tried to mulligan when I drew only one land, but arena decided I didn't want to do that and started my turn anyway.

At a later point, I had mana available for a -2/-2 removal on my turn but was not allowed to play it, the oppponent's next turn they added a +1/+1...result: ultimately, I lost the match.

Normally, arena is pretty stable, but this cycle has really been frustrating from a usage perspective. This isn't the first time I've run in to this same "Instant" not playable issue since FF launched. Originally, I assumed it was b/c I was not aware of a specific change in rules or something, but if that is the case, it needs to be explained in a better way through the UI.