I've now encountered this issue in numerous projects and I can't seem to pinpoint when exactly it breaks, but it works as follows:
At some point in my Painter project, I lose the ability to use the Physical Projection tool anywhere in my project. On any layer, in any capacity. This bug applies only to the 3D view, and I can still use the tool in 2D. Furthermore, regular projection works just fine in both 3D and 2D.
I've attached a screenshot of what it may look like, where upon beginning to paint, some particles do appear on my mesh and the animation time counter starts, but nothing is painted on.
This bug has persisted across numerous versions of Painter and is still present in the latest as of now, 7.4.1. I use this tool quite a lot in my workflow so I find it rather valuable.