[Richard L]

First of all, 2x 0.6 is not equal to 1x 1.2. (read page 8 of the user manual).

If the failsafe is setup correctly, the "B" light should go solid. Try CCW the WL until "B" light stops blinking.

Here is the how the system proceeds:

System is trigger -> "B" light comes on -> if the flow is less than the WL -> "B" goes off. When "WL" and flow is very close of being correct, the "B" ligh just oscillates.

CCW the "WL" and tell me if oit stops the "B" lioght from blinking.

Your problem was to assume 1x1.2mm = 2x0.6mm. So reducing the WL a tad is your answer.