Hi Theo and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, proposed preliminary tries (if have not been done) would be to consider/try a RESET. A reset is both a test and a try of a fix. As it implies, a reset would force the unit to revert back to factory defaults removing glitches and config errors but would include memories, presets and user preferences. After a reset, the initial setup would have to be performed. If have not been done and should you venture to try: Please click HERE.
May have to be done a number of times.
This is very critical - a reset however would not be corrective of an internal hardware concern; but it would be confirmed. In some instances, it may even expose other issues.