Hi @effectual!
The Sensory Percussion 2 Ableton Plugin save menu is designed intentionally to make it difficult to overwrite your standalone sessions and inputs. This guardrail is in place to stop users from accidentally overwriting work.
Once sessions or inputs are loaded into the Sensory Percussion 2 Ableton Plugin, saving actions default to the Ableton session itself. So when you hit command/cntrl + S your work is saved: you will not lose it by quitting Ableton, but it is saved within the Ableton session, and doesn’t overwrite any Sensory Percussion 2 session file you have saved elsewhere on your computer.
Saving as... from the plugin, is essentially an export action, and it probably means that you intentionally now want to access either your .sp2 (session) or .spi (inputs) from the standalone, or save them somewhere else on your hard drive so that you can load them into a different Ableton session with the Sensory Percussion 2 Plugin.
This saving workflow is also in place to protect the ability to run your sensor audio back through the plugin and edit your set later on (which is a really fun use-case for the plugin):
If the standalone was set up to overwrite .spi files in the plugin, and you recorded a performance three months ago, the tuning of your drums will have changed and you would not be able to recreate the performance and edit sounds in the kit by re-running your sensor audio back through the plugin.
Since the .spi and .sp2 (and also .spo) files are neatly saved in the Ableton session when you save using the Ableton file menu (or simply by pressing command/cntrl + S), you don’t need to worry about accidentally overwriting work you did using the standalone app.