Subtracting Not Working as Expected

Hello -

I am working on subtracting Current Data with Past Data using a unique ID to find the last historic value for each unique item. I have successfully calculated the previous value by using the following DAX function:

Previous Data = 
'Table'[Current Data]
    - MAXX(
        FILTER('Table',
            'Table'[Index]
            = EARLIER('Table'[Index]) - 1
            && 'Table'[UID] = EARLIEST('Table'[UID])
        ),
        'Table'[Current Data]
    )

Now that I have this value, I want to subract the each individual row from 'Table' [Current Data] from 'Table' [Previous Data] to get a delta/change value for each row. I used the following as an example:

Delta = 'Table'[Current Data] - 'Table'[Previous Data]

However, when using the above "Delta" calculation all of the values result as "0", and I cannot understand why this is happening.

Below is an example of what I would expect to happen with the delta calculation:

Thank you in advance for any assistance!