Back in the day, (old school mechanic) I would have gone for the earthing of the light connections but, having taken the whole front light assembly out to inspect the wiring, there are no obvious earthing issues. It's all very modular now.
I'm not even sure there is a conventional relay to operate the indicators. I certainly can't find it. The clicking sound of a relay emanates from the instrument cluster and, having pulled the dash panel to look, it appears to be just a sound generator for driver information. I think we might be into circuit board territory but I don't know. Any ideas would be welcome, thanks.