The nightly build version used last week is still normal, but there is a problem with the ‘kicad-msvc.r22985.450b0c9e27-x86_64’ downloaded today.
It is correct to open the schematic diagram from a *.kicad_pro file with kicad, but it will not work if you open the *.kicad_sch file directly with Eeschema.
From your title I first thought that Eeschema was not working at all in your latest KiCad, but if that was true, then it also could not be started from KiCads project manager.
Could it be that just the file association between *.kicad_sch and Eeschema does not work?
Does it work if you first start Eeschema in “Stand alone” mode, and then open a schematic?
It is confirmed that Eeschema’s standalone mode does not work. No window will be displayed in Windows 10 64bit, but it can be found in the task manager.
I just re-verified the previous version. Until yesterday’s “kicad-msvc.r22977.3269f45776-x86_64.exe” is still normal, only today’s “kicad-msvc.r22985.450b0c9e27-x86_64.exe” Eeschema cannot work.