Strapi v3.5.4 filter with OR operator doesn't work correctly

System Information
  • Strapi Version: 3.5.4

Hi everyone, I’m quite new to Strapi and I’m struggling with one task.
In our project we have collection-types Articles and Stores with relation Article can have many Stores.
I’m trying to do filter with OR operator where I want Articles with some store ID OR Articles that have field belongsToAllStores with boolean value set to true. Example of the query:
articles?_where[_or][0][stores.id_eq]=1&_where[_or][1][belongsToAllStores_eq]=true

The problem is it doesn’t return Articles without Stores. It returns all Articles with store ID 1 and all articles that have belongsToAllStores=true but only if they have filled some Store.

Any idea how can I do this?

Kind regards,

Michal