Sorry, had to ask about the high beam switch position, you never said they work correctly for the first 15 minutes of the ride, that data point would have eliminated asking about the push position of the switch.
Anyway, it could either be the headlight switch (LSZ), it's a computer in itself, or the high beam switch. I'd say more likely the LSZ.
If you pull the switch and hold it (flash to pass) do they stay on?
Is the headlight switch in the auto mode during your testing? If not, try using it in the manual "on" position to eliminate the auto mode causing the issue.
If it were mine:
I'd use NCSexpert to rewrite the coding to the LSZ just in case any of the coding got wonky.
If that didn't work, I'd look at the voltage on pin 2 & 36 of the light switch when switching the high beams on and see what it's doing. If you get 12v then the problem is downstream.
Here's the schematic for the Bi-Xenon circuit, it's really pretty simple, all the complicated stuff is inside the LSZ.
