Thank you for confirming.
Do you recall it jamming up at all during the prior usage?
I ask because what you are experiencing indicates that either the internal drive shaft has snapped, or the gears are stripped.
Both of these issues are fairly common, unfortunately, and are the result of a poor design - these drive parts are made of plastic for the gears and soft aluminum for the shaft, so they are damaged pretty easily.
If the discs jam up at all (I've seen this happen just from a tough tomato core or a very fibrous carrot), the torque from the mixer motor causes the gears to just strip out. This can happen too if the speed is too high as the gears can overheat and essentially melt.
No matter the cause though, there is really nothing that can be done at this point other than to replace the unit.
It is new enough fortunately that you should be well within the return policy of most any retailer. So your best recourse here is to contact the seller for a return/exchange.
It would also be covered under the 1 year kitchen aid warranty, but dealing with the seller is going to be much faster and easier.
Overall, unless you are very limited on space and/or budget, you'd be better served with a freestanding self powered food processor that won't fall victim to this type of wear.
I can recommend some other options for you, if you'd prefer to go that route, and have the option of returning/exchanging this one for a refund.
Best regards, ***** ***** for the news,