Subject: RE: Alternate names in view selection formula.
Are you using Desktop private on first use, or server private etc? The former will work with @Username.
I suggest you do something to find out what values the view indexing process is getting for your two values. Something like, create a copy of your view, change the selection formula to SELECT @All, create a view column that has the formula @Username(1) and a column that has the formula fieldname. Are they really identical for any documents?