Lawless,
The reason why it doesn’t work is because NLCD Urban and Land cover are in WGS84 while the Tree canopy is GRS80, which are virtually the same. The way to fix it is to determine which projection to choose. To do this you use gdalwarp. I have found you should make 3 new images all the same way, from the 3 various old images, roughly 30 minutes on my system, each. I have found just changing the 1 image that it wants results in other errors saying to use gdalwarp again to change it to a different image usually having to do with +towgs84. The following code is an example of how to set them up and run as a GRS80, obviously if you want the WGS84, replace it where GRS80 is. I just had this exact same problem with the 2016 NLCD files and this ran the BELD4 to completion.
gdalwarp -overwrite -s_srs ‘+proj=aea +lat_1=29.5 +lat_2=45.5 +lat_0=23 +lon_0=-96 +x_0=0 +y_0=0 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs’ old_tree_image.img new_tree_image.img
gdalwarp -overwrite -s_srs ‘+proj=aea +lat_1=29.5 +lat_2=45.5 +lat_0=23 +lon_0=-96 +x_0=0 +y_0=0 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs’ old_land_image.img new_land_image.img
gdalwarp -overwrite -s_srs ‘+proj=aea +lat_1=29.5 +lat_2=45.5 +lat_0=23 +lon_0=-96 +x_0=0 +y_0=0 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs’ old_urban_image.img new_urban_image.img
Insert the new names of the images into your text file and this should do it.