Excel Paste as Image Issue

It's not altogether clear to me, from your description, exactly what the issue is. Nevertheless, let me offer the following as an addition to the suggestions from NikolinoDE​ :

There are some key combinations that work  to get sections or whole screen images. For example, when I need to get an image of a section of an Excel spreadsheet, I use a key-combination to clip the image of the portion of the full screen that I want. That key combination is (on my Mac) Shift+Command+4. For example, I used it on a section of a spreadsheet that's been shared on this forum to get this image, a small corner of the overall spreadsheet.

A Google search for key combinations to do various screen grabs yields different results for Windows vs Mac. Take your pick for what works.