Jay,
There is not a defined size limit, its really the available storage on device that is the limit, a 100 GB mmpk is not unheard of...
What type of content is not showing up for you?
It is possible to put content or use cartography in a mobile map package that is not supported for display by the particular application or version of ArcGIS Runtime that is being used.
Tile Packages (TPK) should work for displaying aerial imagery in most applications.
Also, reading up the comments in this post...
It is best to have all content in the same coordinate system. The runtime will not project TPK or VTPK layers on the fly, the coordinate system of the map and the Tile Package and Vector Tile Package layers must match.
mark