How to fix count and view pages incorrect when indexing data with multi-term reference fields

This question is not specific for Solr.

In general it isn't required to index all combinations individually, but one document with a multi valued field.

Are you positive that Solr is indeed indexing all combinations, not creating just one document per entity/translation? (Note that if you have a multilingual site, the Search API will create one search item per language per entity.) Did you look into the Solr index and check there?
As @mkalkbrenner wrote, this is not the standard behavior, so in that case it would seem some other module is interfering here.

In case you do have a multilingual site, maybe you are just missing a “current language” filter?

Apologies for taking so long to respond. I've found all I need to do it tick "Unique values filter" in the processors for the index. I can't believe I missed that!

@dubs I don't have a "Unique values filter" on my search index processors page. I even tried upgrading to the 1.x-dev release, but I still don't have it. Are you using some other contrib module that provides this functionality?

Oh - you are using SOLR and I am not. I think that is why.

Hello,
I don't think this is due to SOLR because I have the same problem with my index search API linked to Database Search and Facet extension.

I have a multilingual site and to filter by language I change the url /en/jsonapi/index/ and
/fr/jsonapi/index/ because the langcode facet does not work.

When I add page[limit]=50 I have 25 items in the data and if I change this limit to 25, I have 13 items while I have 66 in total.

Did you add a “current language” filter to your view?

Hi - I'm sorry for not responding sooner - I am sure I did!

What was missing was to tick the dedupe filter - can't believe I missed it!

This can be closed now.