Job class change

I was a PT Cashier working in the customer service desk for about two years without my job class getting changed. About two months ago I switched to grocery (third week of October) and my job class is still PT Cashier. The only reason I switched is because my DM approached me about becoming a GRS during a public serves event and I agreed. Additionally, I’ve worked 40+ hours a week for the last year and a half and still not full time. Is this the same for anyone else/ does it usually take this long or am I just missing something.

P.s I have ROIed multiple times