SU2021 Changing Textures

I’ve recently upgraded from SU2018 to SU2021. My standard textures look completely different when applied - very dark. See the attached image. The light brickwork lower down is as it should be and the dark brick on top is as it now comes in using 2021. You can see in the edit panel that SU still thinks it’s applying the light unsaturated texture. It’s happening with all textures, not just this one.

What is causing this? The only solution I can see at the moment is to rebuild all of my texture libraries from scratch, which is a huge job. This never happened with previous versions of SU. Any suggestions?