Is there anything in the server php error or access logs ? ? Make sure you have error reporting enabled in your php.ini file for that local box as well so it outputs something we can act on.
I've installed it on the following configs, first up an old 16.04 ubuntu with PHP 7.2 and MySQL 5.7
This version: ElkArte 1.1.7
Current version: 1.1.6
GD version: 2.3.0
Imagick version: ImageMagick 6.8.9-9 Q16 x86_64 2020-12-04 http://www.imagemagick.org
MySQL version: 5.7.33-0ubuntu0.16.04.1
Alternative PHP Cache: 5.1.19
Memcached: 1.4.25
Zend OPcache: 7.2.34-18+ubuntu16.04.1+deb.sury.org+1
PHP: 7.2.34-18+ubuntu16.04.1+deb.sury.org+1 (fpm-fcgi)
Server version: nginx/1.16.1
Next up is my home server with is running docker containers, so this is an Alpine version in the containers. This is mariaDB 10.5 and PHP 7.4, mostly the latest versions of items
This version: ElkArte 1.1.7
Current version: 1.1.6
GD version: bundled (2.1.0 compatible)
Imagick version: ImageMagick 7.0.10-48 Q16 x86_64 2020-12-12 https://imagemagick.org
MySQL version: 10.5.8-MariaDB-1:10.5.8+maria~focal
Alternative PHP Cache: 5.1.19
Zend OPcache: 7.4.13
PHP: 7.4.13 (fpm-fcgi)
Server version: nginx/1.19.3
And last up is a ubuntu 20.04 box W/mariaDB 10.3, php 7.4, pure long term support packages here.
This version: ElkArte 1.1.7
Current version: 1.1.6
GD version: 2.2.5
Imagick version: ImageMagick 6.9.10-23 Q16 x86_64 20190101 https://imagemagick.org
MySQL version: 10.3.25-MariaDB-0ubuntu0.20.04.1
Alternative PHP Cache: 5.1.18
Memcache: 1.5.22
PHP: 7.4.3 (fpm-fcgi)
Server version: nginx/1.19.7
So the main deltas are 1) iMagick, 2) Nginx vs Apache, 3) PHP (apache2handler vs fpm-fcgi) None of which I can really see making the difference. I'd also be curious if anyone is running apache / apache2handler has tested the addon.