I let Opus display the columns 'Name' and 'Target' when handling .url files. After editing a .url the 'Target' column doesn't get refreshed for a while even after a manual refresh with F5. Only renaming the .url or restarting Opus helps.
If you edit the URL file using the Properties dialog, Opus reflects the change automatically.
Edit it by hand (e.g. in a text editor) and it doesn't seem to update.
I think we get the information from a Windows API so the OS itself seems to be caching the values unless told to refresh them, which the Properties dialog does but a text editor or similar won't do.