Issues with Packing of tech maps, using and importing the export sbsar created in designer

I am trying to create a custom export template for sampler that is a modificaiton of the Unreal4 template that includes the height map in the alpha channel.  The graph exports as expected w/ 3 outputs, Base Color/Normal/ARMZ tech map from designer, but when I publish to sbsar and import into sampler to use as an export, the channels show up as expected in the export window, but the export hangs, and sampler will not export, stuck at 0%.  I have also tried setting the channel usage to the correct usage for the RGB channel, but that exports individual map files, so not sure what I am doing wrong....any help would be appreciated.