When I was playing Arena on PC, I had Ugin the Ineffable on the field. When I used his +1 (Exile the top card of your library face down and look at it. Create a 2/2 colorless Spirit creature token. When that token leaves the battlefield, put the exiled card into your hand.) it exiled the Eternal Wanderer (alternate art version) as the face down card. However it showed as a mostly invisible card. The only thing showing was the top bar of the car (usually where the card name goes) but it was blank of any text. My game then preceded to lag significantly and any cards I cast after that would not appear on the battlefield but any effects they had would take effect. I eventually got the Eternal Wanderer into my hand and cast it. It didn't appear on the battlefield but I was still able to click the battlefield where it should be and activate its abilities. When it went to the graveyard, it showed as a blank card with placeholder text. None of this changed when Ugin went to the graveyard either. All while this was happening, my game began to lag more and more.