Just had the same issue on PC/Steam.

I wanted to play Vibrance normally (not its evoke cost) and I had the correct mana to activate both abilities, but it wasn't giving me the option to cast with 2 red AND 2 green, only with 2 red OR 2 green. Thought that was a bit weird, but figured it probably wasn't a big deal and would resolve easily if presented with the correct mana values.

I manually tapped two mountains for red, a Lush Oasis and Ruby, Daring Tracker for green, and a Three Tree City enchanted blue by Shimmerwilds Growth (for a total of 6, including the spare blue from Shimmerwilds) and it still used the mana incorrectly when I played the card. The red ability resolved fine, but for some reason the game used the spare blue mana instead of the second green, which made for a payment of 1 colorless, 2 red, 1 blue, 1 green.

Attached the log, hopefully it helps.