After an update, as mentioned in the subject, my S-Pen is failing to connect. Resetting the S-Pen will occasionally reconnect it, but seems to disconnect again. Rebooting the device does not help. The pen is fine, this started happening after the update (the same update that introduced new AI capabilities to picture editing, amongst other things).
I'm betting on some conflict with the update at this point, which would discount the last two possibilities you mention (too much of a coincidence). As for system file corruption, an update could have led to this, but that would have many other symptoms.
You can also use the on-board diagnostics - it's designed to show you the results of self tests for items within the Samsung Device. It's a watered down version of what we use as engineers.
By way of more details, the S-Pen still seems to work (draws on the screen in an applicable app). The air command icon opens up when holding the pen near the screen. Tapping the icon using the pen reveals a menu of options, but above those it does say that the pen is disconnected.
