Editor Viewport manipulators invisible/not rendering correctly - 4.20

Hi,

Working with 4.20, the pos/rot and trans manipulators (and some other classes such as nav modifier) have not been rendering correctly when in lit/unlit mode in the editor viewport. We are using the forward renderer as part of a vr project.

This is consistent across all machines running the project in the studio/on home machines.
We temporarily swap to Wireframe mode to see the manipulators in the viewport.
Examples below:
Lit/Translate - invisible:

Lit/Rot - visible:

Li/Scale - strange little triangle:

Wireframe - as expected:

And an example showing a hint of the arrows/manipulators occluding some of the decals in the viewport:

Are there any settings/conflicts that may be causing this?. Naturally, flicking to wireframe stumps the workflow.

Thanks