Why isn't my inventory updating in real time after backend adjustments?

Why is inventory not updating in real time when it is adjusted in the back end? I.e. if I no longer have a product and need to remove it, it still shows up in my inventory despite zero on hand and archiving the products. I waited for the month to end so it updates on the first of the month but it’s still showing inventory that I removed yesterday. Very frustrating. Can anyone advise or help?