Unexpected syntax for {% cache %}

[rellafella]

All of the included custom Twig tags bundled with Craft seem to work except for the "cache" tag. When using {% cache %} I receive an "Unexpected syntax" error.

Potentially a separate issue, but code hints and autocompletions for custom tags would go a long way here too.

Not sure if it is something with my config, however it is a pretty standard project setup.