Not sure if it's same with you guys, but I got the issue because the scripts aren't loading. Upon checking errors I found out that:
1. The extension gets the script from
http://ssl10.ovh.net instead of the community.allmangasreader.com
2. The "Content Security Policy" (CSP) on the manifest.json doesn't have the domain thus preventing the script to load.
3.
http://ssl10.ovh.net provides the script perfectly fine once the domain is added to the CSP.
I tried to edit the manifest but it doesn't do anything. What solved it for me is by creating a copy of the extension files, edit manifest.json, pack and load to browser. Funny thing though is that it gave me a new extension ID - ahecjkdkicjidlnnnpegolhnhdpanill
SCREENSHOTS OF AMR AND manifest.json:
sdaxdaxdeaxddadeadadxd.JPG [ 125.15 KiB | Viewed 2514 times ]
xddsccsdwedw.JPG [ 138.22 KiB | Viewed 2514 times ]