Photoshop Exports Different Colours

I'm shooting with an A7R ii in Adobe 1998. I do alot of flash exposure blending.

I'm exporting TIFF Adobe 1998 layers and opening them with Scripts > Load files into stack.

When I save the PSD and try to export a preview JPEG with Photoshop the colours look washed out.

I found that if I take a flattened TIFF back into C1 and export the JPEG with C1 the colours are fine. But saving to JPEG with PS has mildly different colours.

This never used to happen. Is there a setting I changed somewhere? I would like to fix this so I don't start screwing up all my backups!

Thanks for any help!