Hmm... I've not been able to replicate this (using the Chrome plugin on the latest codebase to reply to this ticket as it happens!). What other plugins do you have running? Perhaps there's something in your plugin/theme that's interfering?
Regarding Bit.ly, assuming it's the plugin I wrote, I'm also using this with no problem.
Due to the way the share page works, it tries to shorten the page url automatically (for sharing) even if you want to reply. To get it working you need to link to you account, either by static key or OAuth2 (via your admin & settings pages).