[OS X Emacs] aquamacs-emacs: "filesets-open" does not open all of the files

[Daniel Branning]

I have created a fileset in aquamacs-emacs (24.0.92.3) into which has 
been placed three *.tex files. The manual says "You can use the command 
M-x filesets-open to visit all the files in a fileset ...." but only the 
_last_ one in the list remains open for editing in a buffer. The same is 
true if I use the "filesets" submenu, and click on the the "Files:" 
entry under the named fileset itself.

Is there a customization setting which affects this behavior?