Many experience issues with pairing their Bluetooth devices after updating or using Windows 8/8.1. There are several resources on the web addressing this issue.
Here are a couple of general links to assist you in troubleshooting your Windows 8/8.1 Bluetooth issue:
https://www.drivers.com/update/drivers-news/fix-bluetooth-windows-8-1/
https://www.reviversoft.com/blog/2013/03/fixing-bluetooth-in-windows-8/
It is also recommended that you contact your PC manufacturer or Microsoft support.