Clownosity doesn't calculate properly, nor are all clownosity items detected by the MM.
One last comment. You didn't tell us - even after we asked - what you typed in to the maximizer, what equipment you had, or what the maximizer said. If I had to guess, you simply asked for "clownosity".
The maximizer documentation - what you get when you press the "help" button - says this:
The only bitmap modifiers that currently appear useful for maximization are Clownosity and Raveosity, so they are allowed as a special case. The weight specifies the required minimum value; only one value is actually meaningful for some keywords, so 4 clownosity, 7 raveosity are the only useful forms.
You have to specify how much clownosity you want by including that number as the "weight" - and it shows you exactly what to use to get 4 clownosity.
Using just a +, or omitting the weight entirely, is equivalent to a weight of 1.
If you don't include the weight, it defaults to 1. Which is to say, if you maximize for "clownosity", you are asking for "1 clownosity". When I did this, it told me:
equip acc2 polka-dot bow tie (+1)
... which actually gives +2. I do have some +1 items lying around, but it decided to go for the +2 one - which is fine - but reported that it is +1 - which is odd, but harmless.
In any case, every test I've done indicates that clownosity is working correctly. If it is not working the way you expect it work, you need to do what we asked: tell us what you did, tell us what you expected (which was hopefully informed by the documentation), and tell us what you got.
Until then, this is correctly marked Not A Bug.