Sorry for the delay. I got tied-up with some business that need ed to taken care of first.
Back to my topic, I am still having the same rendering problems. Also, this has nothing to do with saving the blender file without saving the edit texture first. Actually, I am not even editing the texture. It is a texture from Textures.com, and there is no need to edit the texture.
My problem happens randomly and all it takes to loose the texture is plugging it into a node that contains a factor property and adjusting its value back and forth. For instance, I could have the blend factor start with 0.3, then change it to 0.7, and then back to 0.5. After so many back and forth’s, it renders the object to pink in the viewport. To fix it for now, sometimes I need to reload the texture, and other times I just need to wiggle the viewport. That is why I asked the members here if I should report as a bug?