Cannot unpin 3 achievements

I just installed WoW onto a new PC and logged in for the first time in a long time. I have three (3) achievements pinned that I cannot remove, for separate reasons.
Dwarfageddon (25 player): I cannot find this achievement. I have completed the 10-player version, but it appears perhaps the 25 player version was renamed to not include the player count, and the 10-play version now DOES include the player count?
Staying Buffed All Winter (10 player): Similar as the above, cannot find the achievement.
They’re Coming Out of the Walls (10 player): I can find the achievement (though it’s just the name, does not include player count), but in game achievement search only results in one version of this achievement.

I have tried standard procedures of resetting my UI per a help ticket, but this did not remedy the problem.

Bump; I need help with this, please. This error still persists, and an in-game GM told me to file a ticket here. On top of that, when I click on my ticket in game, the “customer support” window opens, but the panel is blank with a pair of spinning arrows.