I believe this is the same problem described here. You need to add the --check-caps false command to the iris container in your docker-compose.yml file, like this:

...
iris:
    command: --check-caps false
    init: true
...

The SAM 1.1 distribution should have this done for you but that change must not have made it in. I think you can still enter the SAM 2.0 EAP if you'd like to start with the upcoming version.

@Michael Davidovich

As a first step I suggest you read through our online documentation to familiarize yourself with common workflows. The extension supports a client-side workflow where you export files to the currently open local folder and handle the source control yourself. To edit client-side, you can use the ObjectScript Explorer to export files. You can also use the Export Code From Server command, which uses the objectscript.export configuration settings to determine what to export. Our extension does not support VS Code's "Download" menu option.

Since the disp class is generated from the spec class you probably don't want to store it in source control but if you still want to export it, you can have the Explorer show generated files before you export a package or if you're using the command you can set the objectscript.export.generatedto true.