When I used the "PlaneSetExeTheatreSwitchV4.exe" the "ETO-1944 Late" planeset was not listed for selection.
If I use the "PSM160SpecialSmallSreen.exe" the planeset was listed. This is a quirk of the two file-managers.
When you select a planeset with the "PSM160SpecialSmallSreen.exe" the program looks for a file named "Planes.pco" which is a list of plane-names.
If none is found then it reads the "FMDir.set" file in the folder, and builds the "Planes.pco" file from the data in it.
However, the "PlaneSetExeTheatreSwitchV4.exe" is a much simpler program, and if the selected folder does not have the "PDir.set", the "FMDir.set" and the "Planes.pco" file in it then it does not list the planeset. Most of the plane-set folders have the three files, but the "ETO-1944 Late" planeset did not.
Having loaded it with the "PSM160SpecialSmallSreen.exe" then the "Planes.pco" was created, so the next time I used the "PlaneSetExeTheatreSwitchV4.exe" program the "ETO-1944 Late" planeset was available.
It sounds complicated, but it is not really. The best bet is to use the "PSM160SpecialSmallSreen.exe" as your file manager