This has happened a number of times.  I has only happened in two areas of the game.  When fighting in Minotaur's Labyrinth and most recently when fighting the Nether Spider.  After clearing the waves on both I see the boss, as my champions begin to enter the screen the screen immediately scrolls to where the previous wave was and is locked there.  I can see the boss health and turn meter and related information.  I have tried turning off auto and moving around but that didn't work. The only way I can tell how things are going is if it is on auto and I click the info bubble and that will show me who is dead and any buffs/debuffs that are going on but that is all I can really see.  If I wait either I die or I win.  But the game continues.  

I am running this on an Android Pixel 4XL.  The version of the game listed is 3.31.0 (however this has been happening for a while so it may span versions, I initially thought it was a glitch until it started happening over and over again).  I am listed as being on the Production1 server.