When I press one key, the whole column registers

There were a small percentage of the Batch 1 NK87s that had the stabilizer screws overtightened from the factory. Loosening these screws will typically resolve most connectivity issues, as well as columns binding to a single key, and a few other issues. Try removing the stabilizer screws, and installing a non-conductive washer to mitigate these issues. If the issue persists, try to re-flash the firmware to clear out any lingering issues.