I use custom settings to store project-specific user-defined configuration settings that my add-in picks up and saves using `OnReadSettingsAsync` and `OnWriteSettingsAsync`. When I open a 1.4 project in 2.0, the add-in does not read the custom settings. I can re-enter them and save them and the next time I open the project it reads them. I looked around in the 2.0 aprx zip file and found the project settings stored in a xml file in a folder called ModuleSettings. None of my 1.4 projects (that haven't yet been opened in 2.0) have this folder. I can't find where they are stored in 1.4. So I'm guessing that 2.0 has a different place to store these custom settings and they are not migrated when opening a 1.4 project in 2.0.
I don't recall seeing this discussed in any of the migration documents I read.