Hello, I'm Louie, and I'm happy to help you today. Hope you're doing well and safe there. I'm sorry that you're having trouble with your bluetooth mouse.
I would recommend first you to run Bluetooth troubleshooter.
Select Start , then select Settings > Update & Security > Troubleshoot . In Find and fix other problems, select Bluetooth, and then select Run the troubleshooter and follow the instructions.
If issue still continues try the remaining steps on the links below. You may skip the steps that you've already performed.
https://windowsreport.com/bluetooth-mouse-not-w...
https://support.microsoft.com/en-us/help/14169/...
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Hope this will fix the problem.
Sincerely,
Louie