If you are trying to filter on a facet in the Visual Editor but it shows no dropdown options, the facet hasn’t been set as searchable in your index settings.
The Visual Editor can only display dropdown values for facets that are marked as searchable. If a facet is filter-only, its values aren’t exposed, so no options appear.
How to fix it
Mark the facet as searchable in your index settings. Go to Index > Configurations > Facets.
Once the facet is searchable, its values will appear as dropdown options in the Visual Editor.
Below is an example of a facet showing dropdown options once set as 'searchable':