idk about 5.4 (i use 5.3) but i changed some setting in M_AutoMaster material blueprint by fixing the error message in the material (not replace the error texture) instead click on the error texture, on the Details, look for Material Expression Texture Base, it should be empty. Locate the texture that was supposed to be there and find and assign them from there.
Thank you so much, you saved me like 3 hours of stress, i was using the automatic substance material and any time i would render it, it would come up with a mess of an object with nothing of how it should look like, even though this is longer, i'd be way happier to do this again and again for each of my objects i have to texture than go through that struggle again
