According to the latest post: We had an omission from our most recent patch notes. We’ve changed when the roster lock occurs for both TW and GAC matchmaking. Previously, your roster did not have ...
I was screwed out of TW today because I left at 2:20pm EDT to fix my mods. When I went to rejoin at 2:59 TW was not even there to join.
That really sucks. If you can, apart from this thread I would suggest DMing a developer possibly (perhaps crumb) just to point to this thread and let him know what happened. He said he takes feedback/issues back from the community for meetings with leadership, designers, etc.
Second to that, I'd chat with support. Let them know what happened so they understand you missed a major event because of this issue.