I think I got this figured out! Yay! I indeed have the correct foot for my machine, so that much was okay. I discovered it was more "pilot" error during the pivot.
Without the walking foot, whenever I pivot in sewing, I lower needle all the way, then lift the presser foot for the pivot. Pretty SOP, I know. But, with the walking foot, I found that I can't lower the needle all the way... about halfway seems to work. It still holds everything in place, just the needle is totally all the way down, KWIM? What was happening when I DID lower it all the way down, the walking foot was forced out of where it screws onto the machine, when I lifted the foot up to pivot. I discovered that about halfway leaves enough room for the walking foot attachment the room it needs.
Hope that is clear. I only bothered to write it all out because I've never heard this problem before (I've been sewing for over 20 years!) and thought if anyone else was befuddled with their walking foot, it may be the same little detail throwing them for a loop.