products not showing in search, catalog or categories

[hathugs]

I have searched all forum posts on this topic and tried and checked everything suggested to no avail. Using 2.4.0  and have many products that are setup perfectly in backend but not  showing in search or in their appliccable  categories. They will show with their  direct url only so they are there. categories are set, product in websites is correct and also in categories, stock is above 0, visibility is catalog/search - but I cannot  get them to show. I have cleared cache many times and reindexed product categories however the reindex of catalog/search continues to give an error 

My elastic search has been failing and has to be reset by hosting every day. Im not sure this is related however? and testing the connection it is fine currently when this issue is occuring.  unsure which direction to try first. any advice appreciated.

[infomochigc53f]

Elasticseach is a little sensitive, we connected via the API and it does not return all the products in the database, the fact the products are not showing in the categories is usually down to a coding problem or a database problem, if you have upgraded this is the worst case scenario, the way to upgrade is create a new instance with completely new install and migrate.

If you upgrade an existing install problems will not show up today, but they will show up tomorrow and be difficult to debug, if you perform a full reindex and also cache clean see if they show up then.