Well it fixed it for that session. After a restart, it failed again. Looks like it might be related to the issue where the Model can't be selected by clicking on it that others have reported.
When the issue is there, you can't just click on the model, it won't become selected.
When the issue is not there, you can click on the model, it will select, and then you can click on the other things like the support blocker and it will work.