You indicated "Drive mode: open drain drives high. ( I tried several combinations with pull up resistor etc no change)".
Here's a note for the pin datasheet:
This parameter configures the pin to provide one of the eight available pin drive modes. The
defaults and legal choices are influenced from the Type selections. Refer to the device
datasheet for more details on each drive mode. A diagram shows the circuit representation for
each drive mode as it is selected.
▪ If the Type is Digital Input or Digital Input/Analog, the default is High Impedance Digital.
▪ If the Type is Analog, the default is High Impedance Analog. This is the only pin drive
mode that can support purely Analog pins.
▪ If the Type is Bidirectional or Bidirectional/Analog, the default is Open Drain, Drives Low.
▪ All other pin types default to Strong Drive.
Hope this helps.