Can't Override Left/Right Master Page

[Angela Akridge]

When I try to apply a Last Page master page to the last page of a chapter
(to ensure that I have a blank page and that the footer doesn't appear),
Frame applies the Last page, and then, after I save, Frame adds the
Left/Right page back in. Any idea what's going on? Thank you for your help.
I've had a few problems lately, and folks have responded so promptly with
suggestions. Thank you.

Angela