When I replaced my two side repeaters for LEDs I had nothing but problems. Sometimes indicating left or right would make all indicators flash. The tell tale done what it wanted. In the end I changed the side repeaters back to incandescent bulbs and it was all fine. Fast forward a few years, during the rebuild I fitted true LED side repeaters, and these work fine with the old setup.
I would replace the repeater LEDs with standard and see how you get on.
With a number of loaned and borrowed parts i started testing
First replaced two LED's with normal lights- no joy
Then fitted the Wipac relay - a little joy, a very faint glow from the dash
So fitted the LED with the extra earth wire- same again, a little glow
At this point i was half happy, it was working but not very bright, so was thinking how could i improve this when i discovered the below replacements, bought one green one, and brilliant, they work great, as bright as the rest of the dash.