Some groundwork: All understanding, both pure from mere thought with no real object, or empirical from perception which requires real objects, follows from the judgement whether or not certain concepts belong to corresponding thoughts or perceptions, such that the logical law of identity holds, and suffices for that which rational agents call “meaning”. It is the same as, “because of this, this is the case”.
That being said, the thesis asks after shared meaning, which is the same as, for at least two rational agents, each understanding is asked to summarize whether or not “does this correspond to this”. That which is being shared does not necessarily arise from either of those understandings, but it just as easily could, re: two people interpreting a common object, or two people interpreting each other. Either way, whatever is being shared does not contain the meaning, it merely contains the properties which enable understanding to judge the applicability of concepts which will then identify the meaning.
In addition, if it is the case that judgement uses the logical laws, from which identity is given necessarily and thereafter validated by experience, given from rational epistemology, it follows that the properties of shared objects subject to mutual understanding may not necessarily be the source of meaning itself, for the simple reason experience may not be extant such that concepts are not even available to judge identity. Insufficient experience may still suggest certain arrangements of properties indicate a possible meaning inherent in it and susceptible to being understood, but can say nothing whatsoever as to what that meaning actually is.
(Where experience fails, concepts are still available by means of pure reason. Under these conditions however, any meaning would be no more than mere imaginings, possibly even illusory, and any truth would be lost)
The problem then becomes, in the case of remote sharing, whether the understanding of the creator who imparts his conceptual identities to the eventually shared object, carries over to any subsequent perception and understanding, or, which is the same thing, whether the properties of the object hold the meaning as belonging to it. This further reduces to whether the properties, if they do hold meaning, is what the remote understanding is dealing with, or is it the original meaning of the creator who imparted the properties that the remote understanding is dealing with. Because these may not be the same thing, re: misinterpretation, where the subsequent understanding misjudged the intent of the creator, from cognitive bias or prejudice or mere expectation, the two kinds of meaning may not be the same, which indicates the true meaning must lie in the understanding of the creator and the object only represents it.
All that to say this: the notion that meaning lies exclusively in understanding does not prove meaning doesn’t reside outside it. Nevertheless, any theory that claims meaning lies outside understanding must still incorporate understanding somewhere in that theory.
Anyway......you asked, I answered. Critique as you see fit.