If we open the page properties, "page-path/jcr:content.1.json" request is going and its taking the node values with first level, the multicompositefield values are stored in inner levels, due to that those values are not getting populated in the dialog.
we can overcome this behavior by changing the constant CQ.PAGE_PROPERTIES_MAX_RECURSION_LEVEL value,this constant value controls the maximum depth of the node subtree under the page /jcr:content node, this can be change by overlaying the constants.js(/libs/cq/ui/widgets/source/constants.js) file.