Installed the new 2.2.1 plugin and tested it out. In the new version it's not possible to add a background image to a section module.
jswebdesign
Could you clarify the detailed steps and screenshot of that part?
I tried to add background image for a section via Layout settings of template without issue.
In a joomla 4 it works, in a joomla 3 not. The problem is only in a joomla 3 cms as far as i can see. The div where the sample background image shows is also not visible in a joomla 3 for some reason. in 2 joomla 4 it is there .
You can backup this file: /plugins/system/t4/admin/assets/js/preview.js
Download attached file >> unzip and replace above file: