Are they solved? I still see a lot of reports of people with issues with ZMK 3 on the 360 Pro. Someone who does switch replacements for the KA2/360 said that there is a design error in the 360 Pro, where on one of the halves the key well flex cable runs through the Bluetooth antenna clearance area. This also explains the high variance: how much the issue affects you depends on how the flex cable happens to be oriented in your unit.

But if the connectivity issues are indeed caused by this, the only real solution is a new hardware revision.