Ring group ring-time timeout

Using a ring group in hunt mode, I’ve set the ring time to 45 seconds. When a call comes in, instead of all extensions being rung for 45 seconds each as expected, the ring lasts for 60 seconds total (45 seconds on ext1, 15 seconds on ext2) and then is dropped.

Is there some setting I’m missing here or is there any known issues in this regard?

Thanks in advance!

FreePBX version: 13.0.49
PBX Firmware: 10.13.66-8
PBX Service Pack:
Asterisk version: 13.7.1