I'd been on and off hunting for a replacement for the old Photon File Validator for use with the new file formats the Photon Mono X used, and stumbled across a solution today that also supports a wide variety of other resin printer file formats.
The software is called UVTools, github link is below.
https://github.com/sn4k3/UVtoolsMessing with it today to solve some of the classic phantom triangles that occasionally show up after slicing files in Chitubox, this software seems far more capable than the old photon file validator but I haven't fully explored the feature set enough to see it's full potential.
But, if you are seeing issues that may be caused by missing layers, unsupported islands, or the pesky phantom triangles, this will help you track those down.