Maybe this needs to be fixed at a registry level but I have not seen a posting to explain what keys should be modified. I have seen references to similar problems with WIndows 7, 8 and 10 so perhaps someone can offer a solution. So now that Chrome has become the selected browser, email links are all going to the Google sign on screen expecting me to use Gmail since I can't change the default to go to Outlook. If I hit the Default Programs button on that general options page, it does nothing. If I go to outlook itself and select file/options/general and use the startup option Make Outlook the default Email program, it has no effect. If I go to the default programs list instead, Outlook is not shown as a possible program. So Outlook is being recognized as a target program there. pst as a file type, it properly is pointing to Outlook.
Until iOS 14, you could have an alternative browser like Google Chrome but link actions would always open in Safari. If, using control panel / default programs / file types, I select MailTo, it only is showing Chrome as a possible program. The default web browser will be used when tapping on a link in any application. This is happening on Windows 7, but I have seen reports on 8 and 10.
The mailto default program type has been changed to Chrome and I cannot set it back to Outlook.