So I tested a variety of mods in my modpack to find which was causing the emotes to stop working- and it seems like it's metamorph.
Obviously when morphed you wouldn't be able to emote- but even when in normal form if you try to use one of quark's emote buttons, nothing happens.
Is there a way to fix this? Should I be asking the Quark team about this instead? Please let me know if there's a way we can solve this problem! :)

I tried right now with 1.6-178 and it seems like everything is working fine... I guess it must be another mod which causing this issue.