Just had this happen. It’s happened a few times before. iOS. I did select Capture Log afterwards as well, but don’t see how I can send that, as it did not download anything to attach nor copy anything to the clipboard.

Just lost a game because of this and other bug.
I was playing a roxanne deck in brawl during combat and opponent cast cyclonic rift. I had 5 lands still open, with multiple playable cards in hand that were bounced from the cyclonic rift. It instantly skipped my second main and ended my turn leaving me with all my cards in hand and no blockers.

Not only that but the guy I was playing used an Ottawara with 1 land open and 1 legendary creature his commander.
How is this possible?

Something similiar happend me today in a Premier draft. Had an activated abbiltiy that I want to use in the second main phase of the opponent. But the opponent does not attaked has nothing to cast in his second main, and so Arena don't ask me an go direct end of turn. Which was to late for me :-(((

I have had this happen to me a few times now.
It can often be the best move to play spells after attacking, but this bug can make that not only impossible but I have lost a number of ranked matches due to this not being possible at random.