Another CHMSL LED Conversion

[1991 Corvette ZR-1]

Since this is LED related discussion, I have encountered a hiccup in my install of the rear four tail lamps. I used Zevo 1157R and they light up great. Problem is they will not indicate a turn signal. It is just a solid state of being on for whatever side is being used to signal. Swapped in old bulbs to make sure it was not the switch that had coincidentally gone south and sure enough they blink.

Hazard flashers on and the LED tail lamps do flash. So is this the case of a required relay to make them play nice when using the turn signal switch? Both hazards and turn signals use a flasher buried in the dash but find it weird the signal flasher is not cooperating like the hazard flasher does.