What you show in your screenshot is normal. Look at the small folder next to the Base Color square. It is showing that you have a texture image map plugged in for the Base Color value. That over-rides the setting in the square. Click on the folder and choose Edit Texture*. A psb document will open and you edit the colour by changing that (you can add layers , text , anything you want. Once done close it and choose Save. The 3D object will update.
If you just want a single colour with no variations across it you can choose Remove Texture and use the colour box next to Base Colour to set the colour instead.
Dave
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Anonymous
January 28, 2021
Thanks Dave for replying. I'm finally trying the 3D feature with 21.0.2 with a tutorial, and got stuck on this Materials thing. I tried your Edit Texture option but the object still failed to update, so I tried your suggestion of deleting the texture, then changing the color in the Base Color box. That got the result I was looking for. Thank you! Also, PS has been crashing once in a while when working in the 3D workflow. As I added in my Adobe post, checking other PS forums, it seems there's been several bugs persisting after the 3D material system was changed to a PBR Metallic/Roughness workflow. So the adventure continues. Thanks again, Bill
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Anonymous
January 28, 2021
Checking other photoshop forums, it seems there've been several bugs persisting after the 3D material system was changed to a PBR Metallic/Roughness workflow. Couldn't find any fixes.