Facet filtering with array attributes returns inconsistent facet results in multi-search

[oscarrBS]

Hi,

I’m facing an issue with facets in multi-search when using attributes stored as arrays of strings.

Here’s how I’m currently indexing one of my fields:

"attributesList": [
  "Tested Applications:Indirect ELISA",
  "Application Dilutions:Indirect (quantitative)"
]

The reason I structured it like this is because each product can have multiple attributes under the same header, for example:

Tested Applications:
 - Indirect ELISA
 - Indirect

Application Dilutions:
 - Indirect (quantitative)
 - Indirect (qualitative)

To simplify faceting, I decided to transform them into an array of strings using the format header:value.

The problem:

• On the initial search, results and facets are correct.
• But when I apply a filter on these header:value attributes, the results update correctly but the returned facets include values that don’t match the initial ones.
• This gets worse when I combine filters (e.g., price range + attributes): I get extra facets that were not part of the initial search response.

I suspect the issue might be related to how these attributes are being structured, and maybe Meilisearch isn’t handling facets well with this specific format. But I’m not sure if that’s the case or if I’m missing some configuration.

Has anyone faced something similar? Or is there a recommended way to structure this type of header:value attribute array for facet filtering to work consistently?

Thanks in advance!