I've been using Memex for several months and suddenly it stopped working. Whenever I search or try to index, I just get the "three bouncing balls / I'm thinking" animation.
I use a lot of extensions but I have turned them all off, to no avail. I have turned Memex off and back on, restarted Chrome, etc.
FWIW, I'm using Chrome Version 66.0.3359.117 (Official Build) (64-bit) on a Windows 10 desktop.