Revolution Slider Media Library Not Loading

Hi, i have an issue with the Slider Revolution plugin that when I go to import images from my WordPress library…it doesn’t work, nothing. The others work such as external image, or transparent background. I did do a plugin check on my site disabling all plugins except core plugins and Slider Revolutions Plugin. Right from the start, it did not work.

This issue is on one of my staging sites called but my main site that its copied from and works fine is

I did have support from the team at Slider Revolution and they tested the plugin and theme and this was the result with his comments;

I have perform conflict test and it is basically your theme customization that cause an issue that you may consult with your developer. Slider Media library feature is actually working in parent (original ) theme but the the child theme you have customized cause an issue. To verify it, you can watch this screen recording

I have a hard time understanding that result that as i haven’t done any changes to the theme in months, just update of plugins and it all worked great for a very long time.

Thanks in advance and your help or advice is appreciated.

Update from support at Slider Revolution;
I can see there are 2 child themes where slider feature is working with one and other one i.e modern cause an issue and may be some code has been added in it. There seems a line of code which I have commented out makes works and removed the conflict. please see screen grab below for the code found in functions.php

Had been fixed by Revolution Slider support by removing the code above.