I’ve been running V1.25 on Win11x64 with no problems. Tried to update to 1.26 and it cannot find fxsoundx64.msi. I proceeded to do a complete uninstall of 1.25 and I still get the same messaging. I also tried with 1.27 Beta, no luck. Did a complete search for this msi file and also no luck.
Normally the fxsound_setup.exe would automatically extract and locate fxsound.x64.msi. But if you seeing this installation error, you can extract the msi by running this command from command prompt
fxsound_setup.exe /extract