By default, Visual Assist ignores strings that are likely not VA Hashtags, including strings that happen to contain only hex characters [a-f] and [A-F], e.g. #cafe.
Current UI: You can allow hex-only strings via a setting in the options dialog for Visual Assist.
Visual Assist build 2231 and older
You can allow hex-only strings by setting HashtagsIgnoreHexAlphaTags to 00:
HKCU\Software\Whole Tomato\Visual Assist X\<IDE spec>\HashtagsIgnoreHexAlphaTags = 00
Note: Visual Assist ignores strings that contain both hex characters and digits, e.g. #cafe1, even if HashtagsIgnoreHexAlphaTags is set to 00.
Set to 01 for default behavior.