BQ79616-Q1: Leakage over the UART TX (when in SHUTDOWN mode) to the ISO7742-Q1 IN pin?

Team,

The custom PCB has the below connection:
    [BQ79616] (UART TX - pin 53)  ---> (IN - pin 12) [ISO7742F DWR] 
There is voltage on the BQ79616 UART TX line when in SHUTDOWN mode. This voltage seems to supplies the Isolator (ISO7742-Q1) with parasitic energy even though the VDD is disconnected from the Isolator supply.
And this makes the battery drains.
-Is the analysis correct?
-Is it a known issue?
-Can this be fixed someways?

Thanks in advance,
A.