Ok. We solved it!! I did a hail mary and rolled back WSJT-X to version 2.2.0, and it is now working.
SOOOOOOOOOO DEVELOPER TEAM: It appears that the Kenwood TS-450 library was broken between version 2.2.0 and 2.3.0.
If you want to repair this in the latest beta version (2.5) I'll be happy to test it.
I think the reason I missed this is that I may have inadvertently skipped version 2.3.0. When I had a problem, I rolled back one version and it did not change.
I'll stick with 2.2.0 until I hear from someone By the way, this is the 64 bit build.