I’ve got this problem since I started the game again after a break of one year, everytime I do some battles or events(it doesn’t matter what battles or events) and then train my monsters and finish the training, it’s loading and then the game crashes and I have to do the training again, at first it wasn’t bothering me that much but now it is really annoying. If you need a video to see I can post a link down here.
Have u tried cleaning cache and re-entering your Restore code?,that might work
I also faced the same problem with hell mode battles which makes me do them twice to complete them: When I win the battles the first time, I get the gem and exp but the game crashes. After the winning it the second time I don’t get any reward but progress to the next level.
In my case, I think the problem was the game is not optimized for tablets because I haven’t faced any problems ever since i switched from my tablet to a smaller device