In the Dock bar on your Mac, right-click the Lightroom icon and select Hide from the menu.
The panels at the top, bottom, left, and right in the Lightroom user interface become 'black' intermittently when you perform actions such as switching between Lightroom modules, or minimizing and maximizing the Lightroom window.
Lightroom CC 2015.8/Lightroom 6.8 and earlier
macOS 10.12 (Sierra), Mac OS X 10.11 (El Capitan)
The Lightroom team has made attempts to resolve this issue to a large extent, reduce its occurrences, and recover from it automatically in case one may still hit this issue. If you're running Lightroom on older Mac OS X 10.11 version, the issue may still appear at times. Try out the latest version of Lightroom and let us know your feedback.
To correct this problem:
Workaround for macOS 10.11 and earlier
When the Lightroom panels appear as black on your Mac, follow the workaround steps given below to resolve this issue:
In the Dock bar on your Mac, right-click the Lightroom icon and select Hide from the menu.
Right-click the Lightroom icon in the Dock again and select Show from the menu.
Lightroom panels should be visible now.
Sign in to your account