GrovePi+ D4 port question--differences among ports or faulty port/pi?

[octopusarm]

Hi all,

I've recently started experimenting with two Grove IR distance interrupters connected via a GrovePi+ to a 3B+. I found that the sensors work only when connected to certain digital ports.

Specifically, if an interrupter is connected via port D4, the sensor produces a digital low output and the red LED light remains on no matter how the potentiometer is adjusted and no matter whether there is an object in its path or not. Connected via D3 or D2, the sensor works perfectly. I've now replicated this on two different grovepi+ units. Additionally, I've noted that this issue occurs after an update to the latest firmware (as of 4 October 2020)

While this doesn't affect the functioning of my project, since there are plenty of ports to play with, I'd appreciate any information about port functionality with the latest firmware update.

Best,

David