The time limit on how much time u have to do ur turn in battle

I was switching my tabs to the music i was listening to so that i could start my next song then i switch back to my supermechs tab where i was in battle and it was my turn. I was positive that i had like 10-30 seconds left. But when i was about to make my move, time ran out just out of nowhere in a flash. I thought i was just seeing things wrong but the dude i was fighting said “???” "Bug?? SO i think this is a bug.