The 50 unit mark is based on plunger position, not actual units left in the pod. It is an estimate.
So there might be a fault with the signal from the pod, basing it on a faulty read on the plunger position.
Where it shows the units left in the pod, it will never be as accurate as your own math. If you know what you have put into it, you can subtract about 7.5 units of deadspace and priming, and that is what you actually have in there.
This thread is extremely detailed, but not very easy to understand. It was kinda tough to explain this all.
The simple guess I have is that there is an issue with that pod’s detection of plunger position. I would not base anything on that 50 unit number they give.