There was some discussion on the topic of recording from phone apps a few months ago. Have you tried the search function in the forum?
Unfortunately the app blocks screen captures so I can't show you. There should be three buttons underneath the program graphic after you select it from the guide. Watch Live, Upcoming and Rec show. Do you see the first two only?
Have no issues on my iPhone XS Max latest OS and 7.9.24 optik tv app.
Try uninstalling the app, reboot the iPhone then reinstall the app. Or create a new password and resign into the app.