Translucency bugs

If i set my translucency colour to white and set the value to 0.5, i get a nice glow.
If i set it to 0.4 i get nothing, if i set it to 0.6 i get nothing. If i set it to 0.4, sometimes i get a bigger glow. i set it to 0.45 i get no glow. It seems completely erratic. It also renders occasionally where the translucency is focused in the wrong area. if the light is directly below a point, itll render as if the light was in a different place. Is translucency a known bug?

Thanks
J

I may be misunderstanting how it works, but it does seem like erratic behaviour. I can send a scene if required.

yes please, scene + images would be appreciated

This sounds like an issue with UHD Cache. Is the same thing happening when using path tracing only? (as both solvers)

Will check this when im back at work and ill provide the scene and images too