This information applies to the latest version
When you open a Nik Collection plug-in from Adobe Photoshop, a warning window may appear behind the plug-in interface. This window informs you that Photoshop will not be available while the plug-in is in use.
This message was introduced with version 8. It helps clarify that Photoshop temporarily becomes unresponsive during plug-in usage—an expected condition. You might also observe this status in your system’s Task Manager (Windows) or Activity Monitor (macOS).
Why does this warning appear twice or stay visible?
The warning message appears once, but may look like it's shown twice:
It is already open behind the plug-in interface.
When you apply changes and the plug-in closes, you may briefly see the warning message again until it closes.
If you move the plug-in window, you can see the warning behind it anytime. It does not block functionality, but may stay visible until the plug-in operation is complete.
You don't need to do anything. You can continue working as usual:
Use the plug-in as intended.
Close it once your adjustments are complete.
Photoshop will become responsive again automatically.
This message is shown to set expectations and avoid confusion—your system and software are working correctly.