Hi Maxim,
late comment, but just had the same issue. Clearing my cache solved the issue.
The scss/css files are cached in browser, whenever saving a document you directly inject the new value. But this doesn’t seem to apply when restarting the modeler/deploying, clearing the cache will force this.
I could remember there were a few versions of early Mx9 where this bug appeared. Would recommend upgrading the 9.6.0 To at least a newer version of 9.6.x.
Also make sure to upgrade the Atlas_core, data widgets, and atlas_web_content to the latest version. This is quite often overlooked.
double-check the theme (folder) → web → settings.json contains:
{
"cssFiles": ["theme.compiled.css"]
}
as this is mandatory to compile the theme