There appears to be an issue with the AV settings on the PVR-93000T and the TV, or the TV settings. I don’t have a PVR-9300T but I’m confident I could have reproduced what you describe by two different methods (1) changing the Humax settings within the A/V Control menu, or (2) changing my current TV’s Screen Format settings.
On the AV settings on the Humax’s A/V Control menu, check that the “Screen Ratio” matches your TV.
Also check the Display Format on the same menu.
(The A/V Control menu is accessed via the Preferences menu.)
If that doesn’t fix it check what the TV is set to for the port that your Humax is connected to.