Imports run concurrently against a model can fail with "Model does not have a valid 'open' state"
This item has been identified as an outstanding known issue. A workaround is provided until the issue is officially fixed.
Issue If two or more imports are triggered concurrently on a model, it is possible that one of the imports will fail to complete with the error "Model <modelID> does not have a valid 'open' state: current state is WAIT_FOR_ALL_TASKS_OPEN".
This error will only occur for imports that are using a model in another workspace as the data source of the import. If the error occurs on an import that is contained within a process, it will also cause the process to terminate.
Imports/processes should be triggered to run in sequence. Avoid triggering an import/process on a model while one is already running.
Another work around option is to ensure the source and target models are located within the same workspace. Confirm the workspace has adequate space available for the models beforehand.