I am facing an issue with my clients website. It is showing as fully secure in Mozila Firfox but not in Google Chrome. Why is that, and how can I fix it?
Welcome! As suggested by @toom if you use Developer Mode you can see what the issue is. Looks like it's a Symantec certificate you're using which is causing the issue, please see blockquote below.
The SSL certificate used to load resources from https://www.paypalobjects.com will be distrusted in M70. Once distrusted, users will be prevented from loading these resources. See https://g.co/chrome/symantecpkicerts for more information.
I will assume you're not aware but Google are dropping support on Symantec certificates that were generated on the old PKI infrastructure.
To further add to this as per Daves comments please see Symantec sells SSL business to DigiCert