When Trying to Pair My PC with my Android Phone, Only a Blue Box Shows on the PC

I'm trying to pair my PC with my Android phone. When I open TeamViewer on my PC and connect to the Android app on my phone, all that shows on my PC is a square blue box. Normally, it would show an exact replica of my Android phone on the PC.

Can anybody please tell me what is wrong here and why can I not do this anymore?

Thanks

HB