Ghost facet filter groups will appear is a numeric value is assigned that matches to a different spec option

[altmoola]

Hard to describe, but when the indexer runs, if a specification attribute option is assigned to a product, and that option has a Numeric Value associated to it (let's say 10). If the indexer sees a completely different specification attribute option that also has a Numeric Value of 10 then it associates that option to the product when really it's not there.

Spec option 1 (Bath Capacity):

Spec option 2 (Max Load):

Product assignment (only to spec option 1):

Resulting facet filter groups (shows option 1 and option 2):

Edit 1: It also only appears to do it if (in this case) Spec option 2 has Search filter presentation set to Numeric range.

[mgesing]

Resolved. It's a breaking change that requires the search index to be recreated.