@wlpdrpat OK issue finally solved with help of a hosting support. It seems CDN was somehow causing the issue. After purging the CDN Cache and changing the settings to “Cache All Query Strings” (was before set to “Ignore Query String”), there’s now no issue with badly visible media library.
Thank you for your help though!
@wlpdrpat Understood, thank you for your quick response, I will try that. I just need to find a different troubleshooting plugin because this one is giving me error message:
http://epiciceland.net/wp-content/uploads/2022/09/healthcheck.png
But I guess there are also different plugins with this functionality so I will look around and let you know about the result.