I also, had this issue. I do not have Gmail. I tried some of the other fixes posted here - but they did not work. The following is from the Apple Help folks and the second one (reset System Management Controller) finally fixed the issue.
1) Reset NVRAM or PRAM on your Mac
Shut down your Mac, then turn it on and immediately press and hold these four keys together: Option, Command, P, and R. You can release the keys after about 20 seconds, during which your Mac might appear to restart.
2)How to reset the System Management Controller (SMC) on your Mac
1Choose Apple menu > Shut Down and wait for your Mac to shut down.
2Press Shift-Control-Option on the left side of the built-in keyboard, then press the power button at the same time. Hold these keys and the power button for 10 seconds. If you have a MacBook Pro with Touch ID, the Touch ID button is also the power button.
3Release all keys.
4Press the power button again to turn on your Mac.