I once had a similar thing happen with an XR650L after changing only the rear turn signals after a fall. The replacement lights were aftermarket and much smaller than the factory Honda lights, as I see you have. The bulbs had different amp ratings (front to back) and that was what the problem was. I stuffed the stock Honda bulbs into the replacement signals (there was barely room) and it all worked fine. Try matching the rear bulbs with new ones for the front (yours are three wire at the front) and see if that works.