Added frame doesn't display

I added a frame to my First Master Page, to hold the Arranger (c’est moi):

It doesn’t appear in the layout:

This seems like ultra-basic stuff, yet I fail to comprehend what I’m doing wrong. Any help?

Welcome to the forum.

In the Page Template Editor I can see that you’ve added the frame to the left variant of the Page Template, but your first page is probably a right page (booklets always start on the right except if there’s a title page or other front matter). Use the L->R button at the top of the Page Template Editor to copy your changes from the left variant to the right variant.

Thanks! That was it. I’d even recently read a caution about L/R. I’d like to claim “brain fog,” but I never got COVID…