Masking sky doesn't recalculate the mask in new picture

Hello! 

I am working with portraits and I have an overexposed sky which I need to mask and then save it. When I first worked with the pictures everything worked smoothly. However, I am unsure what I might have pressed but calculating the mask on another portrait in the collection doesn't work correctly anymore. It always uses the same picture in the collection for the mask, which ofcourse shows the sky incorrectly in other pictures. 

However, if I exit the collection and go to another picture in another collection, then the masking sky function works as intended again which leads me to believe I have accidently locked down some setting or something. 

I have updated graphics drivers, Lightroom, uninstalled and installed Lightroom, purged camera raw cache and now I am out of options. It keeps on masking the sky after this one specific picture no matter what. 

I'll add pictures for reference. First picture is the mask after the picture that works correctly. The other picture is an example of how the incorrect mask shows on another picture. Manipulated the faces for privacy. 

Please help as this is a time-sensitive project and I have been stuck on the masking for 2 days now.