I'm a beginner doing a simple planter, for which I downloaded a model (a cactus plant with the soil & planter beneath) from Blenderkit addon in Blender 2.93.
Everything just looks good in both material and render views, and materials are visible in render result also. But after Exporting it into gltf(.glb) file the downloaded 3DModel(CACTUS WITH SOIL) doesn't have any material for them and is simply shown in white color, whereas my planter looks absolutely fine
I downloaded a porcelain material for it from the same Blenderkit add-on).
I'm using EEVEE
Also tried changing all the options while exporting to .glb, but nothing helped. Tried opening the glb file in https://sandbox.babylonjs.com/ which showed the same result as my 3D viewer
I downloaded it from the Blenderkit which you can see in the image, and later I deleted that pot and placed the plant and soil in my planter.
This is what it looked like when exported to a .glb file and viewed in a Windows 3DViewier