When picking up shard 44 in the citadel of loyalty I was in combat when picking up the shard, it completed the collection cast and disappeared upon collection the rest I didn’t receive the achievement so I could get the mount, upon running the command to tell which one im missing the only false is 44. upon going back to the location the shard is still missing.
Exact same thing happened to me yesterday, shard still isn’t present. I’ve submitted a ticket to blizzard but they didn’t do much to help. Kind of a “too bad so sad” attitude imo.