Your profile shows you are using 2019, but if you’re on 2020 you may be seeing something that is the same as a support case I have. Here’s an excerpt from my reply to that case, starting with a way to show the issue (start the steps with 2019 and 2020 closed):
- Put some of your tinted materials into a collection in 2019 and 2020 (using File Explorer)
- Open that collection as a secondary pane in 2019 Materials.
- Drag each one into the In Model pane. They remain the same looking.
- Repeat 3&4 in 2020. The In Model version becomes the original texture, not the tinted one.
A work around, which may be tedious, but not take too long:
- In a 2019 file, lay down every texture you want into the scene. Like, paint bucket at least one face with each texture. Save.
- Open the file in 2020.
- Make a new collection, and drag the In Model textures into the new collection pane.
That seems to create a collection that behaves itself.