That should work.

You are connected to a vCenter I assume?
Check what this returns

$global:defaultVIServers

Start by looking at the .TXT file.
Does this return the paths, one per line, no blank lines?

Get-Content H:\Temp\VMXPaths.txt

Do you get any error messages when running the script?
How did you run the script?
Any entries in the vCenter Tasks/Events? Check via the Web Client.