When attempting to import an Excel import template, the logo and text turn red then does not import. There is no warning or error message:

This has been known to happen with images that are copied/pasted from the clipboard into the Excel import template's 'Default thumbnail', 'Thumbnails' and/or 'Other images' tabs. Try saving the image as a valid image file (e.g. .png, .jpg, .tif, etc.) and then importing them into the tab using Excel's Insert toolbar: