Bug fixed, thnx for notifying me
Please redownload the game
I also have the same issue. For me it happens from the very beginning, if I start the game the intro plays and the tutorial starts, but the heart never gets filled or bigger.
I have restarted and redownloaded several times, and also tried to delete the save data but that didn't help unfortunately.
This only happened for me for the bought PC version, the demo and the android apk work fine. I hope this helps and thank you for all the support.