I had this happen twice, once recently - wanted to report it as a PIREP.
In flight I was attempting to change the airport (AF-5500, SeaRey). I hit the COM button to pop out the radio, then used the knob to begin entering the airport ID. At some point while twisting / tuning, the input controls to the EFIS stopped responding. The display (altitude, heading, engine instruments, etc.) continued to update. But I could not enter the airport ID, nor back out of the radio panel.
Both times I eventually did an in-flight reboot (I was in severe clear VFR conditions) and everything was fine. It might be pilot error, though I wouldn't expect anything a pilot could do should lock up the input controls. After the in-flight restart I was able to enter the destination airport without incident.
Screenshot attached.
Regards,
-Ed Harris