You write "These trees differed only in the relative placement of five enantiornithines closely related to the Avisauridae forming a polytomy with this clade in the strict consensus tree (Consistency Index = 0.453; Retention Index = 0.650)". Given the CI/RI, this is either a "soft" polytomy – note that one instable taxon suffices to collapse the relevant nodes of a strict consensus tree, see e.g. this graphic – or a semi-"hard" polytomy, i.e. lack of discriminating features/inferred change along this part of the subtree.
Using a phylogram, i.e. a tree with branch-lengths proportional to the amount of inferred change, one would directly see the difference (see also my post using your data matrix)