Default App Bugs

I perform a repair install. In File Explorer, I see a .wav file. The very faint checkmark icon next to it seems to signify that there is no default app. Double-clicking on the .wav opens a dialog, "Select an app to open this .wav file." That dialog indicates that the default app is 32-bit IrfanView.

First questions: if the system already considers IrfanView the default .wav app, why is it not displaying the IrfanView icon next to the .wav, and why is it not opening the .wav in IrfanView?

In the dialog, I click to confirm IrfanView. Then I click the option to Always use IrfanView for that .wav file. IrfanView runs and plays the file.

I close IrfanView. I double-click again on the same .wav file. The same dialog appears. It appears not to be recording IrfanView as the default app - for .wavs in general, or even for that specific .wav file.

In Settings > Apps > Default Apps, I type .wav. This confirms that 32-bit IrfanView is the default app for .wav files.

That example uses .wavs. Similarly with other filetypes. For instance, the dialog confirms that Microsoft Edge is the default PDF app. Yet the selected PDF file does not open immediately in Edge. Instead, again I get the baffling dialog: it admits that Edge is the default app, and yet it asks which app I want to use.

I performed the repair install in the hope that it would set the system back to stock condition. It seems the installer assumed this was a personalized arrangement that I wanted to preserve. Even so, I am now repeatedly indicating that I want to change the arrangement. Yet neither a reboot nor even a repair install are able to convey that message to the system.

What should I do now?

See if any of these restore default app reg keys will help.