After the new update your creatures don’t get +4/+4 when matching red gems while Koth’s third ability emblem is on the battlefield
Came here to report the same thing.
ETA: Playing on a Droid (Samsung Galaxy S20)
I just noticed this too
@Oktagon_Support
I’m jumping on this bandwagon. Played 3 games in training grounds against different opponent Planeswalkers to confirm, triggered Koth’s third ability, the token support appears but no buffs are awarded to any creatures after that. It’s only been happening since the update.
It’s not just Koth. Any time you have a card or ability where destroying red gems triggers something, nothing happens. Zendikar Incarnate is also useless. He doesn’t get pumped when you match red gems.
It’s not just red gems. Landfall cards like Prism Array and Zendikar’s Roil are not working.
Having this issue as well
Hello guys,
Thanks for letting us know about this issue, it was fixed in the last Data Push! 
Rebeca