Tyvar the Bellicose ability not resolving for all Elves

I've been playing a Tyvar edh deck for some time, and when elves have a mana ability granted from another source, the mana ability doesn't trigger Tyvar when it resolves.

Ex: I have a Level 5 Joraga Treespeaker, Tyvar the Bellicose, and Gnarlroot Trapper. If I use Gnarlroot trapper's t: add {B} ability, Tyvar's ability triggers and Gnarlroot gets a +1/+1 counter. If instead I use Gnarlroot trapper's t: Add {GG} ability granted by Joraga Treespeaker, Tyvar's ability does not trigger. I have found this happens very consistently across games.

Start by reproducing the listed Joraga Treespeaker, Tyvar the Bellicose, and Gnarlroot Trapper scenario, comparing the direct mana ability with the ability granted by Joraga Treespeaker. Trace how granted mana abilities resolve and how Tyvar's trigger detects them; done means both abilities consistently trigger Tyvar and the Elf receives a +1/+1 counter.

Written by the indexing model from the issue text.