Can’t rate someone after item is shipped

Level 2
So I’m a seller and buyer buys something from me that requires me to ship the item. I ship, he receives, but now I can’t rate him. The option is available but when I click on it nothing happens. Has anyone experienced this. This is the third sale that I couldn’t rate the other party after I shipped the item and it was confirmed he received it.
Level 6
Its glitchy. The workaround is to use offer up website instead of app. Go to inbox and select item message. Submit rating
Level 4
In addition to RevivalGypsys'
Have found the rating system to be somewhat lax in acknowledging sales to rate a user. Usually takes a day or two (after both parties have rated each other) marking an item Sold, to have it actually register. GLTU 👍😉