I was playing against the 5* ironman. The ai cast his house party protocol. It created three countdown tiles. I proceeded to hit him hard in order to remove the countdown tiles like it says. I hit him four or five times for well over 5000 damage and it negated each one but never removed a single tile.
I just had this happen as well. Oddly, once I matched away two of the tiles, the damage from my next Fear Not, Mi Gente (well in excess of the House Party threshold) still didn’t remove the last tile, but it did go through.