Belt of the firebringer does not trigger in 0.38 anymore

Platform, device and operation system
Android, Huawai Mate 20pro

What were you expecting to happen, and what actually happened
I am using the the “belt of the firebringer” giving me a change of 1% per red gem to burn the enemy every round. Since 0.38 the effect never triggers and often there are 20+ red gems on the board at the beginning of the round.

How often does this happen? When did it begin happening?
I played about 50 fights with the configuration and it didn’t trigger once. It worked in 0.37.

Steps to make it happen again
Equip a rare “belt of the firebringer”. Fill the board with red gems and kill the opponent with a spell. Repeat this over and over again and wonder why the enemy is never burnt.