Detail view darker from the preview in the Photo Grid

Hi Helen,  

Thanks for reaching out. We are sorry for the difficulty with Adobe Lightroom.
Please specify the file types you are working with and specify the cameras from which the photos have been taken. Are you editing this specific set of images for the first time, or have they been processed prior? Does this also happen with any JPEG files or RAW files from other sources? Has this started to happen with recently shot images only? Have you tried any troubleshooting steps? 

While some settings are embedded within the RAW image files like Temp & Tint, which is by default.  

Below is an example of a raw image that has been imported for the first time into Lightroom, and no adjustments have been made yet. 

Suppose you are noticing any other changes in the images. One of the reasons could be the RAW defaults within Lightroom (version 3.3 & above) which sets default settings for importing raw file format images in Lightroom based on Adobe defaults, camera-specific defaults, or custom presets.  

Check this article to understand, create your default settings and troubleshoot the same. 

https://helpx.adobe.com/lightroom-cc/using/raw-defaults.html

If this does not resolve the issue, please export some images as originals with settings and share some sample images with us to check if it is a file-specific issue.

We hope to hear from you soon.

Regards, 

Sameer K.