Using either latest Embeddium 0.2.2 for 1.16.5 or Rubidium 0.2.13, cables don't render connected between blocks.
But if you hover the cursor on it, it will show the outline properly going from one side of the block to the other.

This will be fixed in a release shortly; in a couple minutes when the beta is finished compiling you can download it here as an interim fix.

I've pushed 0.2.4 with the fix.

Thanks for the quick response and fix. Tried both and works as expected now!