No program guide

The guide is blank, only partly filled in, or the programs do not match what is actually on.

1. Does your source publish a guide at all?

Not every source does, and a source without one produces an empty guide no matter what the app does. Open Sources and look at the row: it says whether a guide address is configured.

If it says there is none, that is the answer. You can add a guide address separately if you have one.

2. Is the guide empty, or filled in for only some channels?

Empty everywhere. The guide could not be downloaded or read. Refresh the source; if it fails you will get a code that says why.

Some channels only. The guide covers fewer channels than the playlist, which is normal and comes from the source. The app can only show what the guide contains.

3. Are the programs shifted by a whole number of hours?

That is a time zone difference in the guide data itself, not a clock problem on your device. The app reads the times the guide publishes. If they are wrong by exactly one or two hours for every channel, the guide is publishing them in a different zone, and the source is the only party who can correct it.