html-class-suggestions is a Visual Studio Code extension that provides completion options for html class attributes based on the css files in your workspace.
Important VS Code v1.11.x
In v1.11 Microsoft implemented a change that makes intellisense a lot less eager in requesting suggestions from completion providers.
This unfortunately had the unintentional side effect of disabling automatic suggestions for this and all similar VS Code extensions. At the moment there are two known workarounds for this:
Suggestions can be called up manually using ctrl+space.
You can change the configuration setting described in the above release notes and set the strings option to true. This reenables the old behaviour.