HTTPS and Mixed Content in the administration panel 8.1

[Tuussooo]

I just upgraded my store from Prestashop 1.6 to 8.1, the store works everything correctly, everything looks good without errors, customers can place their orders... but in the administration part I have mixed content errors.

In the store configuration, SSL is enabled and activated for all pages, I have cleared cache, SSL is enabled in the database, but for example the catalog->stock link does not have https, and when I press it it makes a Ajax queries in http and blocks the result, not being able to access the page, almost all ajax queries are made in http so it fails in many places.

I'm desperate. I've been trying everything I found on the internet for 2 days and nothing works.