Lee,
Thanks! I've been trying the workaround as previous noted. I was trying to create a master then deleting the column guides. That worked but as I created a new master the margin guides were picked up seemingly at random. Today I was going to look at that again and report back what I saw. Masters A & B were for pages with photo captions (L& R) and C & D pages with photo captions (L & R). What I found was that all master A-D were master A! This is new. The pages that were previously set up retained their original masters. P5 was still master C (the original master C before this random change), page 6 is okay with master A, page 7 okay with original master B, page 8 okay with original master A.
BTW - I started this project with facing pages, but changed to individual pages per my commercial printer's requirements.