Posted this in Technical support too but I'm not sure if that is the exact place for it.

Hi All,

I hope this isn't a stupid question (I'm still learning this massive game) but I truly can't figure it out and SE customer service is useless. My SMN is 50 and is almost to 51 but suddenly my exp count is red with a red circle and slash by it and is frozen at a number. I am gaining no exp from anything. When I switch to another class, it is back to normal but SMN is locked. Please help!