Fender 62' AVRI Jazz Bass hums when Chrome ashtray covers are on.

Issue: Chrome “ashtray” pickup covers cause hum. When covers are removed, hum goes away and bass is completely silent.
Just hovering the covers over the pickups cause an increase in hum, getting louder the closer they get to the pickup.

What I’ve tried so far:
-Alligator clips from bridge to bridge chrome cover
-Alligator clip from different grounds in the controls to covers
-Grounded copper shielding behind pickguard
-Continuity through all grounds in the circuit to bridge, control plate, output ground
-Purchased a new set of Fender Licensed chrome covers
-Demagnitized new and old covers with watch demagnetizer
- tried different, amps, cables in different rooms in my home

What I have yet to try:
Different pickups
Plugging in the guitar OUTSIDE of my home.

Any ideas on how to remedy this would be greatly appreciated.