We have added a sum of 8500 products to the Magento 2 store we are developing, with up to 5100 products in a single parent category.
The expected result would (of course) be that they all show up, granted, when their status is set to enabled.
The actual result is that at least 75% of the products do not show up on the front-end. They are however visible on the backend.
When I select all the products and set the status to disabled and afterwards back to enabled; all the products show up perfectly fine.
But only until a re-indexation is run, then it reverts back to showing only about 25% of the products in the categories at the front-end.
We have tried setting the "Use Flat Catalog Category/Product" to "No", to try and see if that even made a difference at all for the re-indexation issue. Which it didn't.
I have found a similar command to the following, which supposedly could solve the re-indexation problem, I have tried to set the memory limit to higher and lower numbers, to no avail.
php -dmemory_limit=4096M bin/magento indexer:reindex
Magento ver. 2.1.5