Absolute World Position in PP Material Returns Incorrect Values if r.ScreenPercentage is different from 100

Unable to repro in new project, so attaching sample project provided by licensee:

When r.screenpercentage is different from 100 (50 or 150 for example), the absolute world position in a post-process material returns incorrect value. This can be observed in my example with a texture project in wolrd-space. With SP 100 the texture stick to the world, with SP 150 the Texture shift/glide over the world.

1. Open attached project
2. Open BugRepro level
3. PIE
4. Enter console command r.ScreenPercentage 150
5. Move player around

Result: Material/ Texture shifts around with player movement as shown in attached GIF

Expected: Material will not shift