How is the syllogism in my question called?
Fallacious. It is based on equivocation, that we can can avoid rewriting it as follows:
"All mortals are males. Alice is mortal. Therefore she's a human."
What we get is not a valid syllogism; see Fallacy of four terms.
The definition of "valid syllogism" is about a FORMAL linguistic pattern.
"Every A is B; every B is C. Therefore: every A is C".
Valid means that every time we plug in terms (predicates, class names) for the schematic letter, IF the premises are TRUE, also the conclusion is TRUE. There is no way to interpret the definition otherwise.
IF we assume that "All mortal are men" is TRUE and Alice is mortal, then necessarily Alice must be a man ("all" means all).
See also Aristotle, On Sophistical Refutations:
[164a] That some deductions are genuine, while others seem to be so but are not, is evident. This happens with arguments...
[165b] There are two styles of refutation; for some depend on the language used, while some are independent of language. Those ways of producing the illusion which depend on language are six in number: they are homonymy, ambiguity, combination, division, accent, form of expression.
[169a] The error comes about in the case of arguments that depend on homonymy [...] because we are unable to distinguish the various senses (for
some terms it is not easy to distinguish, e.g. one, being, and sameness).