last night I expected the AXBB to work as you described but after downloading the manual

at the bottom of page 19
8.1.1 .Digital isolated ports.

Port#1 pins 2. to 8. are isolated outputs. These outputs contain high speed 10Mbit/sec
optocouplers and an N-channel Mosfet transistors.
The outputs can drive upto 500mAmps of current upto 24Volts voltage levels.
The high current capability of the output transistors makes these outputs ideal to drive
relays, solid state relays and other signals which require isolation.
19/29

on page 21
8.3 .Charge pump safety circuit port

There is one charge pump safety circuit integrated on the board in port#1 O1 CHP output.
The charge pump circuit senses the charge pump pulse stream signal from the controller and
if the signal exists then the output is switched on and if it cuts then the output switches off.
The charge pump can be used to control a safety relay to cut power when the software is not running on the computer.

Unless I have missed it
I have not seen an explicit ref to all output being switched off as I would of expected

My be another AXBB user can confirm

John

PS
have you contacted the manufactures ?