it happens both for hdris in environment and with textures for materials
with the hdris happens that the scene keeps rendering black (as there is no light)
with the materials, they just render gray, even in the material editor the render gray…
i tried to delete the ones stored on the temp folder under asgvis in C: and mixed results happened, after deleting the files, it loaded the hdri but not the material textures… when i tried to make it load again the amteriasl textures, it crashed…
is it a ram problem?
or more of a file conflict thing?
hdri… make sure the map is set to Environemt, by default it will be set to explicit map channel (i think off the top of my head)
as for textures, they need to be saved to the hard-drive and you need to make sure they are linked correctly to that path. downloading models from the internet (if you are that is) will not render properly without running into issues.