When selecting a local background file, no background appears. Using a URL works fine. (I've also exported my backup.json to chrome, and everything works fine there.)
nightTab version 3.61.0 init.js:2:9
data version 3.61.0 no need to run update data.js:46:17
Error in parsing value for ‘-webkit-text-size-adjust’. Declaration dropped. reset.css:10:29
Unrecognized at-rule or error parsing at-rule ‘@-ms-viewport’. reset.css:15:14
Unknown property ‘text-decoration-skip-ink’. Declaration dropped. reset.css:61:28
Unknown property ‘speak’. Declaration dropped. icons.css:16:9
Unknown property ‘-moz-osx-font-smoothing’. Declaration dropped. icons.css:24:27
Unknown property ‘speak’. Declaration dropped. form.css:198:9
Unknown pseudo-class or pseudo-element ‘-moz-color-swatch-wrapper’. Ruleset ignored due to bad selector. form.css:332:21
Ruleset ignored due to bad selector. form.css:428:43
Ruleset ignored due to bad selector. form.css:434:43
Unknown property ‘user-select’. Declaration dropped. link.css:104:15
Unknown property ‘-moz-osx-font-smoothing’. Declaration dropped. fontawesome.css:10:27
Stylesheets without CSSOM changes reparsed to check for errors. Refresh the page to also see errors from stylesheets changed from CSSOM and from style attributes.
This log was taken after clearing the addon data and closing / reopening firefox.
I then loaded a local background file, but the error log was the same, (even after closing / reopening)
Loading a URL background also resulted in the same errors, but does display a background.