In the blueprint world, the crafting recipe shows as a 1 Copper Plate to 3 Copper Wires ratio on all levels of assembly machine, where the Nauvis machines run at 1 Copper Plate to 2 Copper Wires. I have full isolation and all researches enabled.

This mod doesn't alter any recipes like that; you must have some other mods that's doing something. I could look into it if you provide a save file, but there's probably nothing to do here.

I have a several mods enabled, but I don't see anything that modifies the cable or the assemblers other than PlanetsLib, which I did start with just PlanetsLib and Blueprint Sandboxes, and the issue didn't happen again, so it's probably some weird interaction. Save file here: https://drive.google.com/file/d/1_iHuymmYrzGFWY5PViaLJJPCFpryKCAA/view?usp=sharing

The only mod I have that I know changes vanilla recipes (not adding alternates, or just adding new recipes) is one that makes space platforms cheaper. No worries if you don't feel like digging through it. I might do a bunch of mod configurations to see if I can figure out the culprit. Just makes me sad that all my circuit blueprints are operating short 50% of the cable :P