The indicator doesn't repaint the signals, and once an arrow appear it should remain
visible. On the other hand there was a bug in version 1.1 which stopped the indicator
from updating in the real time. This bug was fixed in version 1.5.
From the chart you attached I can see that you are using version 1.5 so you should
not experience any problems.
There was no signal at the yellow tick on your chart because the green area between
the two red areas didn't reach the minimum elevation which is set by the sensitivity
parameters. If you set those parameters to 0 you should get a signal in your case.