I’ve tried swapping the relay with another relay and the problem stays in the same spot, so I don’t think it’s the relay.
The relay is labeled “R1” engine which is not very descriptive. My understanding is that this drives the DME itself. I don’t know what powers it.
Labeled K6300 here:
https://www.newtis.info/tisv2/a/en/r56-cooper-s-hat/RFPlNdP