Error with the multi-select dropdown filter on BigQuery when it doesn't have a value

I haven't been able to filter with the multiselect option for dropdown filter a variable in Bigquery. It's asking me to provide a parameter type for empty array values. I have been working with this:
{{ {RT$BQ_TYPE: 'STRING', value: null} }} ; but still doesn't work. Many hours spent trying to do a really simple thing! so annoying.

Hi @PaulaG,

Does this query work in SQL mode (as opposed to GUI)?

Like this: