So I just played a ranked HS game.
On turn 29 I play “Al’Akir the Windlord”, a known Elemental.
My opponent plays “Reno, Lone Ranger”.
On turn 30 I draw “Kalimos, Primal Lord”. It’s glowing orange since on previous turn I played an elemental. I play it, it provides me with the Invocations options. I choose the “Invocation of Earth”. And… nothing happens. My board is as empty as ever, I only have Kalimos, even though the conditions to cast the Invocation (“played an elemental last turn”) were fully met.
I have a Firestone online recording of this game and I can provide a link to it if it’s allowed and needed.