G. E. M Anscombe makes the following distinction between Wittgenstein's use of sense-less (sinnlos) and nonsense (unsinnig): (page 163)
We must distinguish in the theory of the Tractatus between logical truths and the things that are 'shewn'; logical truths, whose character we have already discussed, are the 'tautologies', and are 'sense-less' propositions (lacking TF poles), their negations being 'contradictions'; attempts to say what is 'shewn' produce 'non-sensical' formulations of words - i.e. sentence-like formations whose constituents turn out not to have any meaning in those forms of sentences - e.g. one uses a formal concept like 'concept' as if it were a proper concept.... Here the attempt to express what one sees breaks down.
Given that logical truths have no true-false poles because they are "sense-less" (not contingent facts of the world), I assumed Wittgenstein would also claim mathematical well-formed formula to be the same. However, Alan Weir suggests that "mathematical utterances" for Wittgenstein may be "non-sensical":
Care must be taken, however. Wittgenstein distinguishes utterances which are sinnlos, which lack sense (including logical tautologies and contradictions here) from those which are unsinnig, nonsensical; it is not clear into which class mathematical utterances fall. One might well think that the game formalist should treat mathematical utterances, on that view just strings of meaningless marks, as unsinnig, not just sinnlos.
This leads to my question whether Wittgenstein views "mathematical utterances" as sinnlos (sense-less) or unsinnig (nonsense)?
Any reference to someone who has considered this question, besides Anscombe or Weir, is all I expect as an answer. I assume Wittgenstein views mathematical utterances as mathematical truths much like he views logical tautologies as logical truths and hence they are sinnlos because they are always true and so cannot have a false pole.
Anscombe, G. E. M. An Introduction to Wittgenstein's Tractatus. (1971). St Augustine's Press.
Weir, Alan, "Formalism in the Philosophy of Mathematics", The Stanford Encyclopedia of Philosophy (Fall 2019 Edition), Edward N. Zalta (ed.), URL = https://plato.stanford.edu/archives/fall2019/entries/formalism-mathematics/.