In our case it was a folding bike we had stored in the port side aft cabin, right beside the clothes locker that just happened to house the fluxgate compass...
The influence of the metal bike wasn't enough to topple the compass unless another metallic object was nearby, like a fishing boat, freighter or whatever...
Whenever it did topple we would unexpectedly do a 90 deg turn toward the passing vessel.. Not ideal under full sail..
Moving the bike solved the issue........