Magento 2 - Product/Category assignment issue

Question

We are running on Magento CE-2.3.5 open source and keep experiencing products disappearing from the website.

When we make product changes/updates and we run indexer:reindex; all products are in their correct category assignments but eventually we notice the products begin to appear under different categories that they are not assigned to.

For an example: A Category has 11 products assigned (6 enabled / 5 disabled) and we see the 6 display on the website as we expect. Then we experience the issue with products being removed/disappearing from the website and then this category becomes 11 products assigned (6 enabled / 5 disabled) but 7 products display on the front end. This extra configurable product does not have this category assigned to it and neither do the simple's underneath it. In order for us to correct this issue we must run the indexer:reindex.

correct-category-assignments

Incorrect-category-assignments

As far as individual product display is concerned: product is enabled, assigned to websites, assigned product to categories, product stock status is in stock, and verified product visibility.

Answer 1

Found the solution for myself and wanted to share:

If you are using ElasticSearch or ElasticSuite for your search functionality and you have multiple Magento2 instances running on the same server (ex. Production server and Staging server); you need to ensure that they have separate values.

ElasticSearch:

In the admin go to Stores > Configuration > Catalog > Catalog > Catalog Search > Elasticsearch Index Prefix

This needs to be a unique value compared to other stores.

ElasticSuite:

In the admin go to Stores > Configuration > ElasticSuite > Base Settings > Indices Settings > Indices Alias Name

This needs to be a unique value compared to other stores.