Hal Crocker

Help! I am trying to import and open tif files in Affinity. When I open a folder with photos my jpeg and Photoshop files open without a problem but my tif files appear as a square with a diagonal line across them. When I try to import one I get three small copies of the photo as strips with distorted long bottoms. Is there a tutorial that could be of help? I have watched a good number but have not found what I need.