Hi Carl,
What you are describing sounds more like a glitch or bug. The Idealization branch can definitely display more than 7 idealizations.
I have had idealizations "disappear" a couple of times, but I do not remember the circumstance (shell or solid, probably fewer than 7 idealizations total). My memory is that the idealizations were "there" in the analysis branch but just were not shown. I was able to get them to reappear in the analysis by doing .... what? Maybe I exited the Nastran environment and re-entered, or might have edited the Idealization in the Model branch and it then reappeared in the analysis branch.
If you find out how to make it reappear, let us know and I can try to reproduce it, or at least document it.
John Holtz, P.E. Global Product Support
Autodesk, Inc. If not provided already, be sure to indicate the version of Inventor Nastran you are using!"The knowledge you seek is at knowledge.autodesk.com" - Confucius 😉