Description:
When you try to run URL Inspection from your Google Search Console for your new web page, sometimes you encounter the "URL not in property" error message. The error doesn't occur when you try to do URL Inspection on your old web pages.
One of the probable cause for this issue is that you've just change your website from http to https.
Resolution:
Open your google search console > click the drop down on your website name > click add property.
On the pop-up window type in your domain name (without http or https) > click continue.
After that, try to run the URL Inspection again. Everything should work normally.