Pretty sweet game. Patch notes imply you already know about it, but just in case it's related but not what you are looking into.
On mobile the level up menu just auto picks something when you take your finger off the joystick.
Thanks for the feedback! The issue listed in the patch notes is actually in reference to controller input. I did not know about this issue in mobile, thank you for reporting it! I'll look into it.
This bug has been fixed. Thanks for reporting it!