OpenGarage Side Mount distance timeout

I have had an OpenGarage for a few years. I have recently moved and am setting it up in a new location.

In the old and the new location I had a roller door where the OG needs to be side mounted. In the new location when the door is up there is nothing outside to reflect the signal of the Ultra sonic sensor. We used be on the low side of a hill facing up possibly allowing reflection off the drive way. Now we are on the high side facing down, outside there nothing to reflect off for about 20m which is a tree across the road.

When the door is down I get a reliable measurement of around 6cm. When the door is up I see no value changes, with the distance value staying at 6cm with nothing in front of it, I can still see the read Count rising. In Advanced I have set Dist. Timeout: to Cap (sto:1). However this does not appear to have helped. I made sure to reboot after making the change.

I was running FW 1.2.0 and have since update to 1.2.3.

Looking at the source code I see that distance measurement is calculated by a timer and a trigger on the Echo pin of the HC-SR04. Does the HC-SR04 have an internal timeout? What happens if the receiver does not get echo back? Will it still trigger the echo pin?