This is a good point to make as it can be confusing.A bit misleading. It does not select gas immediately, so don't panic if the switch to gas is delayed.
Quote from manual "In order to prevent unintended switching to gas operation during refuelling, the electronic
system starts gas operation of the refrigerator after the motor has been turned off for 15 minutes. "
to add to your comment with maybe some additional useful info .....
The Dometic Fridges don't show the fridge as running on Gas until they are actually running on gas.
However ... the Thetford Fridges with Auto Switching immediately appear to switch to gas, with the display showing operating on gas, even though there is this approx 15 minute delay before they attempt to actually ignite.
(Found these details out whilst trouble-shooting my Thetford)