I am using Grid for my healing. I have noticed you can activate the feature Ready Check from "Status < Ready Check < Enable" and then "Frame < Center Icon < Ready Check (mark)". I'm so sure that this was supposed to work, but when I'm in raids and the Raid Leader makes Ready Check, it doesn't response or make anything. I think it has worked some few times, like 1/20 of all Ready Checks it works, but generally it doesn't work.
What can be the reason to Grid not showing Ready Check?
Nopes, you can't see who is not ready unless you have been promoted.
So unless someone did a lot of work making it so the grid plugin synced up with everyone elses plugins and pulled the info from the raid leader... this is not going to work. As that would be a lot of work for very little gain, i dont see it happening.
Ok then, but what about the addon "GridStatusReadyCheck". What does it do? I tried installing it, but nothing really changed.
All that happens is that when a readycheck is announced a tick, X or ? appears in the centre of each players box telling you thier answer. Tick for ready, cross for not and ? while they are deciding. As has been mentioned before only the raid assistants and raid leader can see the results, at least on the defualt, never tried to change it.