Your link didn't help.
My mark forums read now shows as
/f/-/mark-read?date=1514490656 so it is changing but not ever going to zero and always higher than the day before even after it is supposed to be back to zero.
Here's what I saw when I arrived (start)
and after going through frontpage news, quite a few forums and marking things read, here's where I ended up (end).
With clicking mark forums read, etc. The count stayed at 44 no matter how many times I clicked the mark forums read.
I log out when I leave and I tried my 64 bit computer with Waterfox. I have the same problem on that.
I've looked at my profile so many times trying to figure out if I need to change something to fix this.
I might sign up under a nym I use elsewhere, zlim, and see if I have the same problem. If not, I'll then compare plodr's profile to zlim's and see if I can fix it.