I figured out my #Primal relay issue. Primal still uses Kind 3 - whilst everyone else has migrated to Kind 10002.

I modified my relays in primal while using nak's stream feature to see what it would write to the Primal relay - and wouldn't you know, it wrote a kind 3.

Welp... that's quite good to know. Time to write a command to automatically convert my 10002 list to kind 3 whenever I change anything somewhere else...