I have created a google cloud console project and enabled "Google Workspace Marketplaces SDK along with other APIs.I have created an OAuth client for the service account and an OAuth client for a web application.
I have configured "Google workspace Marketplace SDK" under tab "App configuration without any error. When I am trying to save "store listing" after filling in the detail, it shows an error without any hint. I am unable to figure out what went wrong.
It seems that there might be a bug on the console interface, you can report it on https://developers.google.com/workspace/marketplace/support#bugs
I've heard that some users have reported to solve it with a workaround.
If you just check "All Regions" it won't let you continue. Even though it hides the region selector, you have to first select at least one region and then check the "All Regions" box."
If that doesn't work, it's better to report it.