How to fix imported mesh falling through ground? (Moment of Inertia Values Correct)

edit

As part of a larger drone project, I have been importing DAE mesh files (made in Blender) for each of the pieces and manually assembling into sub-assemblies and finally the full drone. However, the drone and sub-pieces all fall through the ground when initially loaded in to the gazebo base environment. The correct Moment of Inertia and Mass values have been assigned for each piece, as they were taken directly from Solidworks. Here is the github repository containing the sdf, config, and mesh folder (containing both an STL and DAE version of the model piece). The files are for a single piece, if it would help to see a completed sub assembly please let me know.