3 out of 15 sliders on one slide has "unassigned" instead of "its value"

Hello Maggie,

Thank you for reaching out and sharing what you are experiencing with your project file.

I tested copy/pasting a slider 25x, and it included all the variables as expected.

I took a look at your file and did see the variables for the sliders, but the names do not line up, which may explain why you did not see them as expected:

This should get you back on the right track.