Disk utility

Try booting to Safe Mode. That boot up takes minutes and clears caches and other things that may resolve your problem.

How to use safe mode on your Mac - Apple Support

Does Disk Utility show the disk when in Safe Mode?

A lot of times just boot to Safe Mode followed by normal boot resolves problems.

soundslike wrote:

When I open the Disk utility, nothing is listed. What is going on?

What do you expect to see?

Are you booted normally or from Recovery—is there an assocaited issue you neglect to say here...?

Is the sidebar turned on? DiskUtility>View>Sidebar

Are you showing All Devices? DiskUtility>View>Show All Devices

Disk Utility User Guide for Mac - Apple Support

Safe Mode did it for me. Thanks!