If what Steptoe is alluding to it's a common fault. The short loom from the bottom of the ignition switch fails. It can either be inside the switch part, or more likely in the loom where the wires are bundled together.
Sometimes the fault with show itself up with moving the handlebars from lock to lock with ignition switched on. It can be repaired, but tbh it's easier if not costly to just replace that part of the loom. Doesn't take long once you have the tank off and drop the ignition switch out to change it over.
I had it happen to a previous bike last year.
The loom should run down the left side of the headstock and should look like this linked
https://www.motobins.co.uk/bmw-parts.php?model=R850 R1100 R1150&bikeref=R1150GS