I upgraded my Mac to OS X Yosemite 10.10.2 recently. Since then the dictionary lookup stopped working in Chrome. Tried both keyboard shortcut and context menu. Know of any workaround for this issue?
I also went to the trackpad part of preferences and unchecked and checked the force click look-up option and it worked again.
I encountered same issue, but that's because I turned on some option Chrome pops up to suggest me to use Chrome itself for dictionary lookup.
Maybe not directly answering the original question, but for some reason the three-finger tap became disabled by default in El Capitan update (OS X 10.11). I had to go to the "trackpad" part of system settings and reenable it. Then it worked normally again.