Like Lock Doc say's more than likely a grounding issue.
I never had any luck with those LED flashers I use these from Amazon. They are cheap, easy to install and they bring em to ya. You keep the original flasher with these and I have found that 1 each side in a easy to reach area like your front turn signals will put enough load for the front and rear lights of the side to which it is wired.
https://www.amazon.com/CUTEQUEEN-TRA...6532433&sr=8-3