Hi ColinJenkins2,
Thank you for reaching Microsoft Community.
Please check first if Wireless display is listed under Optional features of the device. Go to Windows Settings > Apps. Under Apps & features, click on Manage optional features. On the next page, check if Wireless display is listed. If not, click on Add a feature then select Wireless display and click Install. After installation, restart your Surface.
After restart, go back Project to this PC page then set these details below:
For Some Windows and Android devices can project to this PC when you say it's OK, set it to Available everywhere
For Ask to project to this PC, set it to Every time a connection is required
For the Require PIN for pairing, set it to Never
Turn off the This PC can be discovered for projection only when it's plugged in