Update. This issue does not exist in the 2020 releases.
The parameter window in the B1 Dashboards query editor has an issue that prevents us from using parameter names. It gives an error "Object reference not set to an instance of an object" if you try to add/remove characters and move out of the field using the mouse. The workaround is to tab out of the field instead of using the mouse.
We have logged this error to the underlying tech provider.