In a DOM element, if you have a rule with a value that are conditioned by a helper and this helper return an empty value, the rule is removed. But if the value reactively change the rule is append in the end of the style attribute. But if it didn't finish by a semi colon, Balze didn't add it and the style is brocken.
Now that order is preserved, it is unclear if it can happen that ; is missing inside inline styles. There is a TODO for that in joinValues method but I would need an example test case for it to fail to see how it fails.