PhysX 3.4.2 Behaves Differently on Windows and Mac OSX [FIXED]

I'm simulating rigidbody vehicles that use only Rigidbody.AddForce for control, representing lift, induced drag, parasitic drag and thrust. Rigidbodies are set to very low drag values as I'm simulating this elsewhere, and gravity still runs via the physics system.

In the 2018.3b1 beta, all aircraft have a maximum speed of approximately half their correct values, on Windows. This is both in the editor and in Standalone builds. I haven't been able to determine which force is out of balance, but doubling the thrust value does appear to more or less correct the issue- handling is unchanged.

On OSX on the other hand, the speed values are unchanged from 2018.2, both in the editor and in Standalone builds. I can't see anything in the release notes that might account for this.

Pending putting a repro project together, I'm just wondering if there're any changes to PhysX 3.4.2 that I should take into account here?

 

Ok- I think I've cracked this and it wasn't the PhysX. Instantiating the test aircraft caused its prefab to lose reference to an aerofoil prefab for each aero surface, so it was dropping back to simplified lift/drag equations. Inspecting the aircraft prefab in the project didn't show anything amiss. The reference was only lost on Windows after instantiation, ergo the disparity.

It does look like this bug has been canvassed widely elsewhere.