Viewport glitch in 3ds Max 2018

[hsnx]

I have this weird white)viewport appearing on top of the normal viewports, it only appears in this specific project. How can I remove it?

[vusta]

probably just one of your reference image planes. Just try the eye icons on the left colum until you hit the jackpot.

[hsnx]

Nope didn’t work.

Here is another picture of it, it remains above all of the viewports
.