Hi, thanks for sharing this issue.
When ignoring tests, we identify those tests by their structural name in the codebase.
If the name of a test changes, the selector used to ignore the test is invalidated. The namespace forms a critical part of the test's name.
We have no other way to identify the test. There is no other reliable identifier that will persist across multiple versions of an assembly while it is being changed. Thus this is caused by a technical limitation that we cannot change or work around.
If you need to change namespaces of ignored tests, I recommend setting the engine to manual mode so that you have a chance to re-ignore the tests before the engine automatically re-runs them.