I tried myself, unsuccessfully as well. There is a check against the value '%Cheese%', which does not exist, hence the absence of results.
I have another suggestion that would work: create a new Custom field, named Dashboard_Txt, with a formula "=ToString($C_Dashboard)", then query from this custom field with LIKE '%Cheese%'.
The drawback is that you'd have to create a formula custom field just for that.
The last option would be to query all milestones, then filter the data yourself in your code.