What I think is being described and what I am definitely trying to describe is a little different
For me it's only happened when the game is lagging and only if back is hit Before the battle screen comes up.
I get an X but no battle shown in the log and the tower is untouched (not lit up like it would be for a crash/disconnection mid battle)
honestly, it's pretty rare and easy to avoid.
I just don't hit war when my connection is testy and if I Do by accident I wait it out instead of hitting back.
Sometimes that means Minutes before the fight screen loads but I'd rather that than loss