High-speed object bouncing for no reason

I have a sphere that gets hit by another object and then rolls along the surface of a perfectly flat BSP box. At very high speeds the sphere will occasionally bounce up into the air for no apparent reason after travelling a variable difference.

Is there any easy way to prevent this from happening?

Have you tried enabling CCD on the object? - this is designed to ensure high speed interactions work correctly.

Yep, CCD is on, also substepping.

heres a thought…
did you Create the sphere model?
if so, did you import collision? (this could be where it goes bad, as the Poly edges on the model are sharp corners/edges, and not a smooth surface)
if you imported collision - disable collision on your model and adde a standard sphere collision component see if that makes a difference.

All of the above is assuming you made and imported your own sphere model though.
Imagine a sphere made out of polygons the edges could cause the effect you see.

Unfortunately, it’s already using UE4’s sphere collision.

Hmm. collision on the mesh disabled?
if it is, is the floor 100% perfectly flat?
it’s not something like the other object hitting it on a slightly angle causing the bounce? (Just like you can “bounce” snooker/pool balls if hit in the right spot)