Why does my Photoshop window become inactive when I open a Nik Collection Plug-in? Why can’t I continue working on other images in Photoshop?

This information applies to all versions

This is normal behavior when any plug-in is open in Adobe Photoshop and doesn't apply only to Nik Collection plug-ins.

This behavior also occurs when using Meta-Presets (Nik Collection 4–7), because Nik Collection runs in the background to apply the different effects chosen.