Twitch Prime not working properly?

Since I linked my Twitch Prime subscription, I have hoped that I can support a streamer "free of charge" by subscribing. Unfortunately this button is grayed out in the app version… But on the desktop version it works without any problems. Can you tell me if this problem is known and if it can be fixed…

I don't think it works in the app, but, as you said, on the desktop. If you've already given away a sub, I think it's normal for the button to be grayed out