I think I have a similar bug (Max FEP set to 0), but reloading the client doesn't seem to fix it, I the bug noticed after eating a meal after a hunt, and not gaining any attributes when I should have gained at least two.
I had eaten some yarrow before the hunt.
Edit: Deleted my thread on this bug since this was posted first and looks to be the same issue.
It was visual for me at least, after I reloaded the client I was able to see my FEP bar again and gained a level after eating some food as normal. Maybe you have a separate issue?
Hm, Yarrow was in fact not intended to be eatable at all; will restart to fix so noone else is confused by it. I can't quite explain the effect you're seeing, but if it's not a permanent effect, there may not be much need to either. :)
"Object-oriented design is the roman numerals of computing." -- Rob Pike