Missing Worksheet with Data Validation List Options

[aleah657]

Issue:
I have a workbook that has data validation drop-down lists. The list options were put on another worksheet. The worksheet is missing from the workbook altogether. The data validation still works.
The data validation identifies the list coming from a range on "Sheet 4." I don't currently have a Sheet 4 in the worksheet tab options (either hidden or unhidden). How is the DV still working if the sheet is completely missing from the workbook? Or, how is the sheet so hidden none of the online suggestions are finding it?
Microsoft 365 For Enterprise
No macros
No data protection

What I Have Tried:
Advanced - Display All Object
Advanced - Show all Worksheets
Maximizing the Excel Window
Unhide all Worksheets Option (grayed out with no hidden worksheets).

 

[ajm]

when you click on the Data Validation icon on the Data Menu, what is diplayed? There is an option that could have Sheet 4 "Very Hidden". its a vba thing.

put this code into Module 1
Sub UnHide()
Dim ws As Worksheet
For Each ws In Sheets
ws.Visible = True
Next
End Sub