prezi keeps telling me that my background image is too large despite it being below max specs

Hello,

I am trying to set an image as background that is 2560*1920 in size but every time I'll try that prezi tells me that the image is too large and I'd need to resize it.
If I do so, the image gets too small to properly zoom in, so I would really like to keep the size.
Would be great if you could heplp me on that.