First, search the help docs and this forum. Maybe your question has been answered! The debugging steps can help, too. Still stuck? Delete this line and proceed.
What I’m trying to do
I was wondering if someone could help me with this issue
I believe the Banners plugin broke at some point when Obsidian updated. Check the Issues page of the plugin’s GitHub for details (the GitHub is linked near the top of the plugin’s description).
Alternatively, you could try out Dune, which is a theme I’ve created. Just download it from Obsidian’s official theme repo if you’re interested.
A Banner feature is build-in.