Xiao nrF52840 bug with internal pull ups?

I was trying to set a pin as simple INPUT but it was behaving as if it has a 10K-15K pull up on it. So I checked the value of the register 0x50000774 (for Pin 3) and it has the value: 110000000000001100 which means that the internal pull up is enabled. The 2 “pullup” bits are set to 11 - even if I change the code to PULLDOWN. Does anyone know what is going on here? I checked the code on Github but cannot find any obvious errors…

I am also attaching an interrupt to this pin and am checking the register contents after that. Could that be related ? Any advice appreciated…

OK- after some checking I have realised that attaching an interrupt with a mode of “change” reconfigures the pin to have an internal pullup. Would be good to know if this is expected behaviour or not…