I reproduced the Category-dropdown issue. The disappearing Category dropdown on the copy operation seems to be an Excel bug. You can see that the dropdown is functional in the downloaded master. Then, the data validation, which contains a simple formula referencing the Categories sheet, disappears when the worksheet is copied into the new workbook.
Strangely, references to other sheets are preserved through the copy operation when they are in-cell formulas. It seems that only the sheet-references in the data validation are lost.
I don’t quite understand why the dropdown is disappearing but I found a workaround. I changed the range reference from a separate worksheet (i.e. the Categories sheet) to some hidden cells inside the Category Tracker worksheet (that are fed by in-cell formulas to the Categories sheet that seem more robust to the copy operation).
I have updated the master to version 1.61 (link above 
) with the following changes:
- Category dropdown references range within its own sheet
- Added
IFERROR()wrappers to Description lookups in case of category-not-found error - Removed “Utilities” prepopulated category from category dropdown
Thanks for flagging this, everyone.
Randy
P.S. The #CALC! error may stem from the fact that the dropdown in the master has “Utilities” pre-selected but that is not a category in your sheets. Do the formulas work when you select something valid? I changed the master to default to empty so it should no longer prepopulate with a category that fails.