Thanks for looking into this issue guys. First and foremost, great tool, looks super cool, and thanks for creating it.
I have deploying this tool into a corporate environment, being used by over 20 really busy developers. The aforementioned issue creeped in just days after the launch. Not being able to resolve it, I opened this ticker by followed the route suggested in the "Support" link.
Specifically, I have checked the list as mentioned in the link:

• check the list of common fixes below;
• make sure Phabricator is up to date;
• make sure we support your setup;
• gather debugging information;
• explain how to reproduce the issue; and
• create a task in Maniphest.

First two are basically suggesting to update various applications, including Phabricator itself, which, as you may concur, is not an option for the purpose of debugging in a corporate installation. I want to be able to install a stable, reasonably tested release and upgrade on my own schedule.
I did however restart various daemons (phd, nginx, sendmail etc). Didn't help obviously.