The part is seeing a simultaneous under voltage and over voltage. There may be some contamination on the board causing 2 cell input pins (VCx) to pull together causing one cell to see a low voltage and one or both adjacent cells to see a high voltage. Resistance to ground on a pin can also cause a high & low cell input voltage.
If the part has been damaged by application of a voltage above abs max to the inputs, either on the single ended or differential limits, the pins could develop a resistive short to each other or to VSS internal to the IC. This can also cause the simultaneous UV and OV. Sometimes only 1 shows up depending on the applied voltage and severity of the damage.
With the EVM a risk is removing the cell simulator with power applied to the board. When one contact breaks at the end of the resistor divider, the inputs are pulled to the supply voltage by the remaining connection. When wiring a board with separate cell connections, touching the cell tap to the wrong input can impose a high voltage on an input. A tool or fixture path to ground could impose an unexpectedly high voltage on a cell input and potentially cause damage. If connection is made with a connector and the wrong pins can contact during connector alignment, damage could occur with some combinations.
While no input should exceed abs max, the VC1 and VC7 have shown to have some sensitivity to transients and were protected on the EVM. Some users have indicated VC10 is also easily damaged and some protection on this pin may be needed. Consider the system operating environment and what protections are needed and if it is on the product board or in the assembly fixture.