The blank, unresponsive gray dialog box issue you are encountering is a has been reported as a graphics rendering bug introduced in macOS 27.2 likely due to the changes in Liquid Glass.
The reason taking a screenshot forces the content to appear is because triggering the screen-capture mechanism forces the WindowServer to redraw the active frame, momentarily overriding the faulty blur/transparency rendering pipeline.
Until Apple releases a patch to fix this rendering glitch, you can use the permanent solution below to prevent it from happening entirely.
Core Fix: Toggle "Reduce Transparency"
The glitch stems from the operating system's attempt to render the frosted-glass transparency effects on confirmation sheets and dialog boxes. Disabling this effect bypasses the bug completely:
- Click the Apple Menu in the top left corner of your screen and select System Settings.
- Navigate to Accessibility in the left sidebar, then click on Display.
- Locate the toggle for Reduce Transparency and turn it ON.
Note: This will change the look of your menus and dock to a solid color instead of translucent, but it completely eliminates the blank, frozen pop-ups without requiring you to constantly take screenshots.
Alternative Workarounds (If you want to keep transparency)
If you prefer not to disable system transparency, you can use these methods to force the dialog box to draw itself without taking up space with screenshot files:
- Use the Escape Key or Minimize: Sometimes toggling focus away from the app using Cmd + Tab and switching back will force a window refresh.
- Restart the UI Server: If the issue begins to happen constantly across multiple apps, you can quickly reset your Mac's interface server by opening the Terminal app and typing the following command, then hitting return:
killall SystemUIServer
This seems to be a bug triggered by something specific to your Mac and some others, because personally I have never seen this on macOS 27.2. In Excel, as in other apps, the dialog box is immediately visible when appropriate, for me.
General trouble shooting steps include a simple reboot, safe mode and creating a test user.
Have you rebooted your Mac? If not, that's the first step. If that does not help, then see if the problem is present when you boot in safe mode. That process performs some system cleanup and clears caches, and also disables 3rd party extensions that may cause problems.
Start up your Mac in safe mode - Apple Support
If that does not correct the issue, test in a new user account. A newly-created user account will have all settings at default, and if the issue does not occur in that new account then it provides guidance on what may need to be changed to correct the issue.
Add a user or group on Mac - Apple Support
Once the testing is complete, the new account can easily be deleted.
Delete a user or group on Mac – Apple Support
Those steps will help to isolate the problem.
It might help to download and run EtreCheck, written by a long-time forum member. The free version is fine. Post the full report using the Additional Text button. No personal information is revealed.
