Position UI Element at game object position - Screen space Camera

Hey guys,
I position some overlay ui effects at the players position when the player dies etc. This worked fine when using a screen space overlay canvas, using

Vector3 screenPt = cam.WorldToScreenPoint(playerPos)

And positioning the ui element at this position.
But we have switched over to using Screen space Camera so we can make use of post process on a ui camera BUT the ui elements are now offset off screen with the above code. Which makes sense.
So I have the game camera, the ui camera and the canvas available in the code, so is there a way to correctly move the ui element to correct position?
Many thanks
Chris

This is not UI Toolkit (formally UIElements) related. See:

(moving thread to more appropriate forum)