BT on Windows 10

One for the technical bods on here.

I run Zwift on a Windows 10 PC. I use it for running and cycling but use ANT+ for this to connect either my Neo 2T or an NPE RUNN.

Having become frustrated with the Runn and it’s bouncing speed I’ve downloaded a program on my tablet called Treadmill Speed Transmitter which allows you to input a speed and it sends this via BT to Zwift on the PC.

Only I can’t get it to work. I’m using a dongle and have tried both a 5.0 and 4.0 one.
In Windows the tablet is paired with it.
However on the tablet if I try to pair with the desktop it says it cannot connect.
If I try and send a file from the tablet to the desktop it fails.

The result is the the treadmill app isn’t being seen by Windows and if it does then it’s not sending the transmitted speed.

If i run the treadmill app on the tablet and run Zwift on my phone it connects immediately.

Am i missing something?