I am still wondering on this as well. It's really quite annoying that you can't tell exactly what's happening, or what it is that's stopping/delaying such a thing.
Mine says I paid the right amount of tax for 2021-2022, at £0. But that's not true if I actually paid tax. I had almost half a year of paying tax, which I assume should have been refunded since I was still below the £12,000-a-year threshold.
The tax account pages just sends you around in circles, or only lets you check on something you've already made a claim for. If I'm waiting on a P800 and haven't received a P800, how do I know if it hasn't already been sent and just got lost in the post?