HTTPS server certificate fails

Is there a way to check the certificate used for HTTPS for errors or problems in general? One of the websites I access is always shown by Chrome as Not Secure. To view the site I then have to click on "Accept insecure website" otherwise everything is blocked. Behind it there is Outlook Web App. When I check the entries of the certificate by clicking through what is shown by Chrome, everything looks fine. My first though was that the certificate is not valid anymore, but it is still valid until somewhere this upcoming June. The issuer CN settings are RapidSSL SHA256 CA - G3, the O settings are GeoTrust Inc., and there is no OU entry. The certificate is issued as a wildcard for *.mysite.com. Other than that all looks fine.

Now, Chrome is still complaining. Is there another way to check what is wrong? Maybe through an app?