Using version 11.0.1.1765.

When I use "Configure Tool" and try to pass the name of the file currently open in a Program Window with #file I get something like "BO49DE~1" instead of the real file name.
#Path returns the correct path, but has the bogus file name attached, too.

With this bug Configure Tools is completely useless right now

If the file or directory name contains spaces it will be converted to 8.3 notation. To prevent this, surround the variable by quotes: use "#file" instead of #file.

The file name does not contain any spaces but it does contain an underscore. Surrounding it with quotes does work however, thank you

You should either document this behavior in the help file or automatically add the quotes. Some programs (like the one I use with this function) simply do not work with the ancient 8.3 notation.