I have installed Manjaro with KDE Plasma on my laptop, and I have dual boot with Windows 10. Bluetooth works fine on the second one, so I can connect devices through it.
Although I don’t have any issues with Bluetooth on Windows, it doesn’t work the right way on Manjaro.
I can turn it on via system settings or Blueman manager, but the scanner doesn’t see any devices nearby such as my phone or wireless headphones. When I hover my mouse over the Bluetooth icon in the system tray, the label appears and displays that "No available adapters found’.
I’ve tried different console commands as:
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bluetooth --help
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sudo systemctl status bluetooth
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sudo rfkill list
And they showed that Bluetooth is currently running and working. It isn’t blocked by Soft and Hard. So, I think that problem is in that fact that my computer doesn’t see any devices with Bluetooth while it is still working.
P. S. 
I’m sorry for grammatical or technical mistakes, or wrong text desing, I’m kind of new at this. If you need more information to help me in solveing this problem, I can give it.