Prestashop 1.7.6.9 - translations not loading - backend

[Repik]

Hello,

I went through many topics, but havent found a correct answer. I'm trying to change translations (I have two on my shop - english and czech).

When I try to enter the translations the window stays as if loading:

And the console shows this:

when I hover over the admin887ckhzzd link at the right side it says:

/admin887ckhzzd/index.php/api/translations/tree/cs/back

Thank you for any ideas what could cause this.

Mike

Edited November 25, 2020 by Repik (see edit history)