Hi Matt,
In what Windows version?
Editing from where? The file properties "InfoEdit" tab or (if in Windows Vista or up) the file properties "Details" tab or Windows Explorer details pane?
Any field in particular or it occurs with all the fields?
I've done a quick test, in Windows 7 and 8.1 (32 and 64 bit) and I'm not seeing any limit in the number of characters, even using the example you refer.