standing at my desk not giving me stand credit

The Apple Watch does not know if you are standing or sitting down or laying down or standing on your head.

It ONLY knows that your arm has been moving back and forth as if you are walking. Wave your arm around and you will get stand credit.

This is a quote from Apple Support website;

The Stand ring shows hours in which you've stood and moved for at least a minute. Complete your daily Stand goal by standing up and moving around for at least 1 minute during 12 different hours in the day. Even if you stand all day, you still need to move around.

The minute that you stand and move around can be anytime from 1 minute after the hour until 1 minute before the next hour.

If you have stand reminders turned on then if you haven't stood yet in the current hour then the watch will remind you to stand at 50 minutes past the hour,this gives you 10 minutes in which to stand and move around before the next hour starts.