I'm really hoping this is more of a PEBKAC issue than a bug.
I have a model where I have added additional geometry to the file. As seen below in Maya (note that I have everything assigned to the same texture "m_feathers"):

When I pull that texture set into my Substance project (Edit>Project Configuration) the project fbx does not appear to update, as seen below (texture name circled to confirm that the same texture name is being used):

However, creating a new project with that same .fbx now has the added geometry :

Has anyone else experienced this and/or came up with a solution or workaround?
Edit:I'm attaching the correct log file from the project that is failing to update the model properly -- sorry, had submitted a log file from the test project beforehand.