Got the same issue but with my back 2 doors. I can hear it try...but to no avail. Child lock is off. And only way for me to open rear doors is through the front doors.

__________________
1991 240sx Silvia swap(gave to brother)
1986 200sx turbo(scrapped)
2008 Honda Ruckus GY6(150cc)swap, stretched(sold)
1989 E34 535i(donated to charity)

1989 E34 525i rhd
2001 X5 4.4i sport