We are using Magento 2.1.8 and believe this worked in Magento 2.1.7 (but the bug may also been introduced sometime else).
When clicking a filter in the shop category, we get the message "We can't find products matching the selection."
We already reindexed and cleared the cache.
We use the Wyomind_ElasticSearch module but already disabled it and have the same result. But after enabling it back and reindexing, we sometimes see one product (which should be more) in the filtered category. Interestingly, the product count shows "4 items", even only 1 is shown.
How can this be debugged?