Everything seems fine regarding settings. But here are some additional tips which you can try:
- Uninstall theme, and install it again
- Re-install WP installation from WP admin > Dashboard > Updates and run Re-install Now
- From WP admin > Settings > Permalinks reset them to default and Save
- Increase WP memory limit to higher value by following instructions here https://codex.wordpress.org/Editing_wp-config.php#Increasing_memory_allocated_to_PHP
- Increase max_execution_time php directive to value higher then 30, although you should be fine with 30 (contact host in order to achieve this)
If nothing if above doesn’t work for you, then I am clueless. Theme is lightweight, and it is working fine for many users, and also on my testing environment, so only thing that is crossing my mind is that there is some server problem regarding WP installation, permissions, or some other misconfiguration. After this point you should definitely contact your host in order to check server error log, in order to check for possible problems.
Another thing which you can try is to install WP and theme on your local machine (localhost) and then to try if it is working. In this way you can test its functionality, and to see if everything is working. Below are some helpful guides:
All the Best!