So after more testing I made a new project, did everything exactly the same, yet this bug never appears, everything is working as expected. I’ve gone over the two projects and they seem identical to each other yet I’ve confirmed on one of these projects the camera world location and forward axis jump wildly left and right by about 10 units when walking backwards for no apparent reason. Very odd.
anyway the fix was to just start again, luckily I noticed right at the start of the project.