There exists invoke expressions on instances, where Java is able to perform the call, yet clojure is not reflectively.
The problem is when the declaringClass of the found method is not public then the call to getAsMethodOfPublicBase uses the found method or searching for classes/interfaces that contain/define this method yet are declared publicly.

This restricts the possible search space. I suggest that if target is not null (e.g. is not a static method), the target.getClass() should be used instead as a root for getAsMethodOfPublicBase.
This fixes my issue.