Thanks for reporting. Hmm, did you find out if there's a pattern when that happens? Like clicking really fast?
For me it happens when I stay in that potion/item/tower screen for too long. If I have to drink 10+ potions of several different potions in lategame, it often occure. You can bypass it by pressing the "back" button on samsung phones.
I haven‘t found out if there is a pattern yet. Up to now it seems random to me. Sometimes I just open the item/potion/ tower screen to look what I have and it happens, sometimes it happens after I transmute something and sometimes or happens after I drank some potions