Different visitor id is getting generated for the sites

Hi Team,

We have a site A,B and C where the tracking is enabled. For the site B, we have set the user id. We have a link in site A to navigate to the site B. When we checked the visitor id, it’s different for the site A and site B. But the visitor id is matching for the site A and C. This issue is happening mainly in the IE.

Could you please help.