Hello,
It seems like baking displacement map on an imported model does not work at all. As soon as the model has been exported, even if imported directly back into Metashape without doing anything results in either a pitch black texture or a completely crunched black/white output. This is very unfortunate as there are instances where you might want to export the model to external applications for ie. better UV packing before doing any final bakes. I have tried exporting and importing as many different formats without luck.
Only solution currently is to bake on a mesh that has not been exported and later reproject the displacement map onto a new model with improved UVs.
I hope the Metashape team can find a solution for this as it creates unecessary friction in the pipeline.