I posted this on a previous issue that is closed so I am creating a new ticket as I am not sure the closed item will be reviewed by anyone.
You can see the description of the issue here.
https://support.aspnetzero.com/QA/Questions/12197/Issues-when-adding-a-new-Metronic-Theme
I am having a similar problem.
customized the stylesheets and regenerated the metronic theme. I copied over the following files from the metronic dist folder:
dist/css dist/js dist/plugins
I replaced the files in the angular project in the folder /src/assets/metronic/themes13/ folder.
After that there seems to be an issue where the left navigation disappears when I am in desktop mode.
When I shrink the window, and it goes into mobile mode I can see the menu although it does have some problems.
When I use the metronic demo there doesn't appear to be any issue.
I am wondering If I need to copy additional files over the metronic into the angular project or I am missing something else.
Thanks,
Kevin