Check your Trash Can (My DU > Trash Can) and see if the thread is there. You may have trashed it by accident.

I did an OP last week I didn't see. And I am not ignoring myself.

I am going to try logging out and logging back in.

They do a substring match, so trashing rat will trash ratchet, rational and so forth. Don't ask me how I found out.

Good luck. But do check the "My DU" lists.
Got me twice today.

I've never logged out of DU before!

Big red button.

SIGN OUT.

But clearing cookies will also do it.

Good luck.