P: Text filtering problems with "Starts With"

I used to use the "Text" option in the Library Filter in Grid mode to select photographs that needed renaming. I used the "Filename" "Starts With" option. It used to filter only files whose file name started with the text that I put into the search box. Now it appears to find any file that has the text in the file name, not just at the beginning. It seems to be looking at the beginning of every word in the file name. I think I first noticed this when Version 3 came out, but it might have been before that.