Running default FTB Revelation, with default key bind for block rotation lock: "K".

When pressing the key, the game freezes for a moment then kicks the user to the server-list.

The game does not crash.

Do you have a server log I can look at?

Nevermind, it's a dupe of #723

This looks like a different issue after all since you're not using sponge.

I believe our server is using sponge. Let me confirm with some buddies and I will attempt to recreate the issue and provide the server log.

If you're using sponge you'll have to report it to them, because I can't reproduce it with just forge.

Thanks, I'll see what they have to say about it