Time Stretch will not work on multiple clips, but it will on single clips

I have several images that I want to change the default duration for. I can change the duration on single clips without a problem, but I cannot select multiple clips and then change the duration all at once. There is a catch however, when I select multiple clips and the timestretch dialog box appears, I am able to select/deselect the link icon, but the time slider/numerical input is greyed out. I am using premiere elements 18.

Thanks