I am having the same ? issue.
Yesterday worked on a model adding materials /textures, all done in material preview mode with Evee enabled plus CUDA and GPU both enabled but I have no need to render.
Saved correctly but when I opened the file this morning the object was all white !!! in preview mode.
Saw this thread and played about with switching between Cycles, evee, cuda etc, went back to my usual settings with evee and cuda and CPU all on and now I have all my materials showing again in Cycles rendered mode but still everything is white in EVEE (and workstation) and no materials in preview mode.
Running V2.82.7 for the last month with no problems. Don’t know enough to be talking of bugs WHY so how can I get the materials to show again in evee preview mode, please ???
EDIT In my case Cycles is working and it is evee which has suddenly stopped working in preview mode !
This can get confusing so here is what is happening now.
Cycles, rendered view all materials/textures are showing fine, but as soon as I switch to preview mode everything is white.
Switch to evee or workbench and again everything is white, so I can only see my materials in Cycles rendered view.
My problem is how to get them to show in preview mode. Thanks.
Another edit: because thinking on this and having looked at earlier autosaves, I think this is a problem caused by my materials not being saved properly (don’t know how else to describe it).
The model was not made by me and it is untidy in places and had lost some materials and textures so i was re doing it. I am using the Material Library add-on and shift + Q was bringing up all the materials which I then assigned to the various parts of the model.
When I opened the model this morning, the materials were showing in the list but for some reason were not being found by Eevee but they were being found by Cycles.
Perhaps I should start a different thread asking about the materials not being saved - sorry, I am a newbie just trying to learn, but thanks in advance for any help whatever.
Yet another edit because I now realise I am getting my Material Add-ons mixed up.
Shift + Q is Material Utilities, still in Beta and only now have I seen all the settings (in the add-ons list) so now I must backtrack my use of these add-ons and get them sorted so as not to cunfuse the render engines!