I recently started getting this “invalid texture” problem. I had edited the roughness of the material.. all seemed fine.. then when I went back to the material I get this.. see screenshot. I think it has only been happening in 2.5.
I have it happen on a few occasions: If there are lots of them showing this then sometimes re-loading the model restores them, but a quicker fix for one or two is
going into the SU texture and adjust one of the colour sliders (then put it back to what it was) it will force Enscape to look at the texture and re-load it into the Enscape library.
(But it is a glitch and shouldn’t happen in the first place)