List filter operator - naming issue?

If I name a test tiddler as #test and give it a list value of a b c then list[#test] shows properly

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but if I name it ##test then it no longer works - did I stumble into a naming convention issue?

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The parameter to the list operator is a reference to a field or index of a tiddler, so ##test is interpreted as the index ##test of the current tiddler.

See https://tiddlywiki.com/#list%20Operator