I play a lot of limited magic on arena (for mobile) and there has been some persistent deck building issues that make it difficult to build a deck for limited. There has been a consistent issue of not being able to view the details of a deck without losing the progress made on what you have built so far. It won't let you use the back button, so you have to close the app and re-open, which puts every card from the draft back into your deck.

The new issue that has come up is quite significant. When deck building I cannot add new cards into my deck. So If I haven't been careful during the draft to build my deck as I go, I will have to log into my PC to finish building it. I can have everything added all at once, but if I remove something and want to re-add it I will have to restart, or build it on pc.