residual voltage on j1/j2 pins 1/3 when trying to use as input gpio

[harelhel]

manual says to remove resistors R1 R2 R3 R4 in order to use as GPIO
however after removal whenever adapter board is powered (even if not connected to Jeston) GPIO pins have a constant ~2.5V voltage.
when changing lines to be as output, voltage does drop to 0 , and tests with scope have indicated it works as it should
examples and code from allied vision GitHub repository was used with same results.
cameras work fine with software trigger but with current situation , HW trigger is impossible.
we tried it with several boards and several adapters. does gpio require an additional pullup/pulldown resistor?

this was tested using a JESTON XAVIER with jetpack 4.6.1/4.6.2/5.0.2 (and as mentioned this behavior was observed when adapter was not connected as well)
2 cameras are allvium 1800 c-040m with
it was also observed when only 1 camera was connected with 12318 cables.
please provide example schematic for connecting to external HW trigger