CHDK bug would always select it after changing other settings
AFAIK, this is not a bug that anyone else has reported. However, it is very easy to enable it accidentally while working in <ALT> mode - CHDK has an annoying keyboard shortcut feature that can't be fully disabled.
See :
CHDK User Manual : Shortcut KeysMaybe I'll add a warning at script startup if RAW is enabled. Either that or allow a script parameter to be used to let you specify if RAW should be enabled (and override the CHDK setting if necessary).
What about the exposure issue? What do you think causes it?
Do you get the same problem when you shoot without RAW enabled?
To make things easier to diagnose, I can post a small test script that is basically an extract of the script's exposure logic.That would make it easier to determine if it's a script issue, a camera setup issue, or a CHDK port issue. If you can run some tests that would help.