When functions are bugged, and progress is prevented by those bugs, then compensation is in order, whether one pays to play or not.
Paying just to get around a bug is not the solution. Testing the functions and making sure they work before rolling out an event is the solution. But when that doesn't happen, then all players should be compensated for progress lost due to bug(s), regardless if they pay or not. All gacha games work this way.
Just add some time to the event. If it takes 18 hours to fix this bug, then simply add 18 hours to the event, that is all.