The issue occurred with the card Nethergoyf.

At a decisive moment in the match, I attempted to activate the card's Escape ability. The requirement for the ability's cost involves exiling different card types from the graveyard. At that moment, my graveyard contained about 15 cards, including Enchantments, Creatures, Instants, Sorceries, and Artifacts.

I easily met the requirement (4 or more card types), however, the game did not allow the ability to be activated. The system simply did not enable the option to pay the Escape cost, even with sufficient resources and cards in the graveyard.

This failure was the determining factor in my defeat, as the return of Nethergoyf with its updated power would have guaranteed victory in the match.