Discrepancy in file count

[goesprotocall]

I'm manually copying files and folders  (thousands of files, many levels of nested folders)  from the laptop (win10) to a NAS and while checking if I got them right, I noticed that the file count in the properties menu (select file>alt+enter) is very weird.

On the top level folder, the source would appear to have more files than the destination
But when I go down the level to see exactly what the extra files are, I would find that some folders in the destination appears to be more than the source.

This is just a simply copy and paste operation, and I havent done anything else to the destination folder yet. What gives?

Also, if I try to group the contents of the top level folder, say, into 3 groups, then get their file count separately, then sum them up. The results dont tally with that of if I were to just get the file count of the top level folder. This actually happens for both the source and destination.

For example:
Source TLF: 1000 files
Source Group 1: 352
Source Group 2: 333
Source Group 3: 346

Destination TLF: 982 files
Destination Group 1: 385
Destination Group 2: 333
Destination Group 3: 357