Whenever I go back into Excel sheet again all the check boxes are unchecked in ActiveX Listbox that were checked off before. How can I stop this?

Hello everyone! Hopefully you can help me with this and I'm just missing something really simple.

I'm having an issue with a worksheet I have pasted into a PowerPoint slide using Paste Special>Paste Link>Microsoft Excel Worksheet (code) Object. 

The trouble is in the worksheet I have a ActiveX Listbox with check boxes in it. 

Whenever I test it like this:

I open the sheet by double clicking on the object pasted into PPT.

In the popup XLSM sheet I check some of the boxes to indicate what tasks have been completed.

I save and close the popup XLSM sheet and "update link" on the object pasted into PPT.

However whenever I go back into the XLSM sheet again by double clicking on the object all the check boxes are unchecked again. How can I make this not happen so that I don't lose all the checked boxes every time I open the sheet? I have 100s of tasks with check boxes and it is not efficient to have to recheck all of the ones previously checked off every time I want to check off a new task.

Thank you for any help or suggestions you can provide!!