Play button control drop out on Ipad

I use an Ipad to control Roon and the play button drops out and is not usable intermittently. I have tried restarting everything involved with no success. Do I need to uninstall and reinstall Roon?

I would try reinstalling the iPad app first.
Is the iPad OS up to date?

Often just restarting the iPad app is enough to clear a bad state. Double click the Home button and flick the Roon mini-screen upwards. It should disappear, taking it out of memory. Then start the Roon app again.