LED signal light issues.

The EL12 is a mechanical relay and requires enough load on it in order to work with LED bulbs. Adding a load resistor kind of defeats the purpose of converting to led's. What you need is a true no load flasher for led's like this one
CF12ANL-01 LED Bulb Electronic Flasher | Flashers & Load Resistors | Car Bulb Installation Supplies | LED Car Light Bulbs | Super Bright LEDs