ignore.conf having no effect on ignoring files

[matt53787]

I'm having a very difficult time with ignore.conf on a particular project. I've used it before with success, so I'm not sure what I'm doing incorrectly this time around. Here's my ignore.conf:

/MyProject/obj
/MyProject/bin

And yet, files there are numerous files in these directories that still show up in pending changes. I have verified that "Show ignored files" is not checked in the options. Any thoughts as to what I'm missing? These files were checked in prior to the ignore.conf lines being added.