There are 2 "pageURLs" that show in the debugger.. I believe the one a the top is really just a visual mapping to what page is being tested, but that isn't the info being sent to analytics....
The "g" value, or the "PageURL" as tracked in Adobe is the second one, the one that shows about mid-way down the debugger in alphabetical order

The one at the top is paired with "Page Title" which also isn't something that is sent to Adobe by default, but the later one is paired with "Page Name" which is the "pageName" value that does go to Adobe.
Check both fields and see if the second one is getting your modified value...
Though, I would suggest that you not modify the Page URL (unless you are just doing it to sanitize PII - like an email passed through a querystring), you can always use an eVar for a "processed path" URL variation... PageURL is really your only truly identifiable value of where the user was on the site, and is only available in Data Warehouse and Raw Data Exports....