Just experienced a similar issue, lost the child theme styles after updating.
How I got around it was to copy the _meta/assets.json
file from the parent theme into the child theme then changed the values of the style
& script
items and the destination item on the bundles to use the child theme path. This way when you make changes through the theme customizer your changes are stored inside the child theme.
"style": [
{
"path": "CHANGE_TO_YOUR_CHILD_THEME/assets/css/app.css",
"name": "app-css"
}
],
"script": [
{
"path": "CHANGE_TO_YOUR_CHILD_THEME/assets/js/app.js",
"name": "app-js"
}
],
"bundles": [
{
...
"destination": "~/themes/CHANGE_TO_YOUR_CHILD_THEME/assets/css/app.css"
},
{
...
"destination": "~/themes/CHANGE_TO_YOUR_CHILD_THEME/assets/js/app.js"
}
]
Create two empty directories within your child theme; assets/js
& assets/css