iirc this has already been fixed on dev branch, I remember someone working on it and putting a commit through for it.

alright, can confirm the issue is present on version r315 of the CUP Terrains Dev Build with the hatchback (sport). I have tried it with multiple other vehicles both vanilla and CUP and all others didn't do it at all or if they did it was almost unnoticeable. I've also noted it only happens while on roads, including runways, and is immediately gone once offroad which leads me to believe, with the very limited knowledge about modding I have, that something with the roads specifically is broken.

the 7th screenshot is what it looks like when you go back to the default transformation mode in editor

In the past I fixed the issue myself simply by placing the LHD first and not moving/rotating it from initial placement in editor. I don't know if that still works now as I haven't really had a need for the already equipped LHD in a long time but I would still attempt it as a temporary solution if you need it.