Buttons on subform not appearing until doc is refreshed

I have a subform with some action buttons on it. I have added this subform to the Memo, Reply and Reply With History forms in the 6.5 mail template. They currently have no hide-when settings, so are always visible.

When I create a Memo form, everything is fine, the buttons are visible. The odd behavior is when I create one of the Reply forms. If I choose any of the Reply options (Reply, Reply with History etc), then the buttons on my subform are not visible until I hit F9 to refresh. If, however, I choose any of the Reply to all options (Reply to all, Reply to all with history etc), then the buttons are visible without a refresh.

Does anybody know what is going on in the depths of the mail template to cause this? If I add the same subform to a form in another database, the buttons appear correctly.

Thanks

Dave