All of my other fsdreamteam scenery seems to work fine with no jumps...
Well, of course they do. The area is different so, even if OrbX Vector is active there too, it's not a given it will always cause a problem everywhere. We surely haven't put any "bumps" in the scenery, of course, and the altitude is correct and in P3D we don't even use any kind of sloped runway ( which are not even possible in V4, they have been added in V5 ).
Could be you just have your Mesh resolution setting TOO HIGH ? Going over 5 mt/pixel resolution is completely useless, since there's no public mesh data source that has a *real* ( not oversampled ) resolution higher than that and, in addition to put extra strain on the PC with no visible gain, going higher than 5mt/pixel causes artifacts due to oversampling errors, which result in bumps or spikes that even if they might not necessarily be visible, might still affect the ground physics.
So, if you set it any higher, put it back at 5mt/pixel, and no more.