I just upgraded to 1.0.8 and updated all the plugins. Now Markdown Notices Plugin doesn’t work anymore.
They are working for me. Have you checked to make sure all your plugins are up to date? How about clearing cache, does that help? If not, please create an issue here: https://github.com/getgrav/grav-plugin-markdown-notices/issues
BTW, just tested on a fresh installation of Grav 1.0.9 (latest) and Admin Panel (1.0.8) and it works fine also. You might need to ensure you have the Use Built-in CSS option enabled.