ID of matrix printed instead of value I have strange issue and cannot find out the solution for that.
I have this field (matrix with some text values): https://imgur.com/a/KaFXubJ

Also I have this entry: https://imgur.com/a/cPMrGul

And this is how it rendered (it shows not value of fields but id of matrix block table): https://imgur.com/a/SR3HgQZ

Here is how it looks like in template: https://pastebin.com/viVbPLqj

I've tried multiple combinations but nothing was solution. Also other fields are works well (fields which not related to "companyInformation" matrix).

So what may I do wrong?
Technically the data you're seeking are under the first matrix block (not the first data of your .companyName - which is not valid)

{% set relatedCaseStudy = reviewFeatured.relatedCaseStudy.first %}
{% set firstCompany = relatedCaseStudy.companyInformation.first %}
{{ firstCompany.companyName }}



Note: If you plan to have only one company, think about a SuperTable field in 'static' mode (only one occurence).