Not sure how to explain this bug.
Basically when I click on enemies or players or NPC nothing happens.
I.e. the usual UI with healthbar and avatar on top of the screen won’t show up, nor the circle below the person.
I haven’t changed anything to GW2 nor my PC, and never happened until tonight.
Please note that left click works for everything else: clicking skills, items, bags, etc.
The bug started happening upon me entering Sparkfly Fen.
It was all fixed by rebooting the game but still wanted to post about it for bug-reporting duty.