The mentioned AMA thread has been up since it was started (Mattew's AMA - Chess Forums - Chess.com) It doesn't seem to have been deleted at all, so I'm not sure why you wouldn't be able to find it.
Since we haven't heard similar from other users, you might want to check out this article: I'm having technical problems! What should I do? but you're also welcome to submit a bug report. We appreciate the feedback 
Ok.
Maybe my brain malfunctioned, but I searched and searched and it just didn't seem to be there. Then, as I said it reappeared later.
If it happens again I'll try to get screenshots and do the bug report thing. 🧐
I would have said it was because a moderator deleted it or it was moved to another category, but i don't remember changing my thread at all. Weird.
Ok.
Maybe my brain malfunctioned, but I searched and searched and it just didn't seem to be there. Then, as I said it reappeared later.
If it happens again I'll try to get screenshots and do the bug report thing. 🧐
Where were you looking? I've seen some topics occasionally not show in the forum list, until someone replies. I think that has happened previously when someone deletes their last post but I haven't had time to do exhaustive testing.
It was in the off topic forum. Maybe it didn't show because someone deleted a post like you said. I had commented in the thread so it wouldn't have been that hard to find - it would have had that little chat bubble beside it.
I went to the 1st off topic page. Then the second, third, fourth and never saw it. I stopped going further back into the pages because I realized that the last replies on the thread titles I was seeing at that point were from 1 day ago, when I knew that the last post made in the Mattew AMA thread was from just a few hours before.
Anyway, it's there now and hasn't disappeared again since.
I've seen this a few times in the past few days. I'll look at a thread, then a few minutes later go back to that page and the thread is gone. Does that mean it's under review or is there some kind of glitch. Yesterday it was Mattew's AMA thread in off topic. I kept looking and looking but it wasn't there
Now it's back today, but the same thing has happened to me on the general chess discussion page. I was reading a thread a few minutes ago. Now I go back to general chess discussion and it's gone - like it never existed.