After clicking the starting crystal (the one that is visible before the Ossirian is pulled, it immediately respawned, which is apparently not something that is supposed to happen.
The respawned crystal was unusable (won’t debuff Ossirian when clicked) and it appears that whatever crystal gets triggered to spawn from that unusable crystal is also unusable.
This was happening every attempt, so obviously, best to leave that respawned starting crystal alone. It did seem to reduce the number of available crystals though.
Others in raid said that other crystals as well weren’t working properly to debuff (but I can’t confirm that since I was off to the side clicking ones that were super far away trying to get them to respawn nearer to boss).