I'm sorry you lost work with this issue. I've made a couple of modifications in changeset 1226 that will hopefully remedy this situation. Here are a few issues that you probably hit here:
1) If you open an old file format in NORMA then the file is automatically upgraded through one or more transforms. The save button is then disabled to prevent you from overwriting your old file without a 'Save As'. This had been a silent process, and VS does not beep if a command is disabled, so you could hit Ctrl-S as many times as you like with no effect.
2) A new file with a DB import was treated as an import, so Save again had no effect.
3) AFAIK, the VS auto-save mechanism is tied tightly to its IVsTextBuffer mechanism. The ORM designer (actually, an DSLTools-based designer) is not a text buffer, and does not get auto-saved like a code file. I researched this once and didn't get very far, but the VS SDK is a huge API and it is quite possible I missed something.
With the current changes:
New files will never disable the Save button, and you will get the following message for upgraded files:
The file format of 'FILENAME' has been automatically upgraded to a new version.
Should the 'Save' command be disabled to preserve the original file contents? The 'Save As' command will remain enabled.
This way, you will know that you need to do a Save As (or make a backup choose No to the prompt).
See other comments on asserts in your other thread.
-Matt