An important update to USD has caused some specific ways of binding materials to no longer be valid. You may run into issues where your materials worked in older versions, but perhaps are not correctly displaying in 2023.1. Specifically showing grey or using their display color.
To fix this issue, please use the asset validator. You can find more information about it here: Omniverse MDL Materials — Omniverse Materials and Rendering documentation
2023.1 before validation
We highly suggest running the validator on older assets as a great way to keep them clean and as up-to-date with the USD spec. In this first release, we leaned towards a manual validation and letting our users decided when it was applicable to validate their content. We’ll be adding an automated process in future releases that can be selected as well.
Let us know if you have any issues!