This may be related to some other problems that others ran into recently. I have already resolved it, but thought I might mention it here, in case some else runs into similar problem.
Yesterday PJRC was in the process of releasing 1.58, so there was a semi-private version for the file to use in preferences, to point to the Teensy installs... Which I used and helped verify that it works. So this morning when the actual release happened, so set the URL back to the official one for Teensy, and wanted to reinstall 1.58. So this time I went to the board manager, and this time did an uninstall of 1.58, told the package list to update and then did an install. Thought everything was fine, until I tried to do a build.
After pulling out a few more hairs, I checked the Teeny tools directory mentioned and found it only had teensy.exe in it. Tried choosing different version and then back, it sill did not work. Hint: when I reinstalled 1.58, one of the messages was the tools were already installed.
What happened, was before I started doing the update, I had compiled a sketch or two and the Teensy app was still running. The actual window was buried somewhere on my screen.
When I told Arduino to remove Teensy install, it failed to remove the Teensy.exe as it was running. I don't believe there was any warnings on this. And as it did not remove that app, it did not remove the directory it was contained in.
So when I told it to reinstall, it saw the directory and did nothing, so I was left with just that one app and the build failed.
I fixed it by selecting different version, then delete the 1.58 tools directory and then tell it to update to the new release and everything is working again.
Not sure if one or more issues should be created, or if there already are ones. But thought I would mention it, in case someone else runs into something similar.
Kurt
Edit: Should mention I am running Windows 11
Nightly build: 20230330
