Hello Travis, and thanks for your feedback.
I am not 100% sure if I understood your problem right: you seem to have troubles with the Post-Process SSAO, but except if I am wrong, I think your problem lies with the “Ground shadows” feature, which is another kind of ambient occlusion.
The problem as I understand it
To try and reproduce your issue, I first uploaded a model with a cube, activated the Ground Shadows in the “Lighting tab” of the 3D settings, and then re-uploaded a new model (the head of a monkey).
When I open my re-uploaded model for the first time, here is the result I have:
You can clearly see that the AO is still the one from the cube I had uploaded previously, and indeed has not changed.
This default behaviour is “normal”, although I can agree that it is not necessarily intuitive in your case: we decided to do so in order to avoid the re-computation of the ground AO for people whose reuploaded model is just slightly different than the original one.
If your issue indeed lies within the ground AO (and not the SSAO available in the post-processing tab), the way to fix it is to force the ground AO to be recomputed: go into the 3D settings of your model, in the “Lighting” tab, and in the “Ground Shadows” menu.
From there, just changing the “Height” or “Shadow diffusion” parameters should trigger the computation of the AO, taking the new geometry into account:
Hope this will help, but do not hesitate to insist if I misinterpreted your issue !