Hey, I just encountered a bug in my ranked game. I was playing Mitsurugi Yummy, did my Mitsu loop, and summoned Zombie Vampire in EMZ. I whiffed on Yummy names but found a Droll in my opponent’s GY, which I summoned to my field. Then I linked off my Vampire for Gravity Controller. My Extra Deck was glowing, and so were my Yummy Synchros. But when I tried to perform a Synchro Summon, I could select Gravity Controller, yet Droll was “locked” even though the card was glowing. I had no other monsters on the field. I think this specific interaction is bugged… please check it out, because it cost me the game. 
Sounds like the Unity resolution bug, where a card glows as if you can interact, but it cannot be clicked.
Nothing we can do to resolve it, as its a Unity engine bug, which is part of why Omega 3 will be using Godot instead.