My solution to the very same problem. I was having a similar problem. Left turn signal switch activation would lead to no turn signals flashing and no turn signal indicator on the dashboard. I started checking continuity and found that the ground lead to the left front turn signals had continuity with the positive terminal in the turn signal bulb socket. The positive terminal on the socket is the round raised portion at the very bottom of the socket that the end of the bulb contacts. Once I saw this, I pulled the socket apart and found the ground was making contact with the positive wire before it made it to the bulb. This was drawing all the current needed for the rear left turn signal and the dashboard indicator. I have some aftermarket incandescent turn signals and the way the socket is set up is not very robust. I put a new signal on and all was solved. Bottom line is that there is probably a ground issue somewhere on the bike. I would check the signals first. I thought it was the relay and I now have three perfectly good relays as a result of chasing that cat for a while. Good luck!
I was having this same problem a couple of weeks ago. I located and unplugged the multifuctional relay under the headlight cowling (small black box on left side). I cleaned the contacts with an aerosol electrical cleaner, plugged it back in and it now works fine. I took me longer to find this thread again to post the solution than it did to actually fix the problem. Good luck! If this doesn't work, I would say replace the relay.