I believe I have had a similar issue, both on my whm, this toon.
First time was in Capperbell Mines Hard, on zone in, all my effects seems to act as if they were disabled, however, the settings menu claimed they were on. I attempted to switch them on and off again, but this had no effect. I also attempted to switch to full screen, borderless full screen (which is what I normally run on), and windowed, and changing that setting had no effect either. Ended up having to exit the game to fix.
Second time was zoning in the Coerthas Central Highlands from Mor Dhora. Same thing, all effects disable and unrecoverable. This time I tried zoning back, no effect, and logging in and out of the character, still no effect. Only completely exiting and restarting the game corrected the issue.

Both times I had been playing for a couple hours without issue before hand.
I'm running on PC. I'm using a Geforce GTX 760, Driver version 337.88 (which as of now is the latest).
Only had this problem since 2.28. The last instance of this error occurred after the latest patch (that is the CCH zone one, which happened this Sunday).