Going over what you’ve described unfortunately it’s not supported. That space parameter is the misleading part. It’s there for consistency. It doesn’t signal migrations support Spaces - it’s a common property not part of the import command https://github.com/OctopusDeploy/OctopusCLI/blob/c3b8420fde34f8755dae93e962486d2cf66d35e4/source/Octopus.Cli/Commands/ImportCommand.cs#L22
If I read this part of your last message carefully you do have 2 different spaces, or at least because on Prod it’s not the default it becomes an unsupported case.
In DEV, the project is located in the default scope, while in PROD it should be located in a non-default one.
We currently only support moving data between 2 servers where they are basically the same, we only intended to have the migrator work for existing scenarios.
Trying to use Spaces is not an existing scenario, and isn’t supported because we are trying to focus our work on a completely new migration tool instead of trying to patch the existing migration tools to work with the changes introduced in Spaces.
If you need to use the migrator to move data between to instances, the only supported approach is moving data between the 2 default spaces on both instances.
I’m sorry if this has caused you a lot of wasted effort, we really do want to ship a great new migration tool it’s just very complicated.