The hearts gained from the Crystal Hearts Quest apparently do not work now that the Valentine's Day timer is over. This is a bug.
My first Crystal Heart will run out tomorrow. I'll wait until the bug is fixed before I use my second one.
Also - charging the Valentine's Day Collections results in not getting the prizes, just the gold coins. Another bug, I assume.
Be careful everyone!
Hope an update that addresses these issues (and everything else) is released soon.