Issue with GPS and copter 4.0.4dev

I’m observing following issue in 4.0.4dev:
Although gps aquires a 3d fix and hdop is good, i cannot arm with cylindrical fence set:
One EKF flag is red (absolute horizontal position). I’m using EKF2.
Sometimes this flag clears itself after a looooong time (half an hour or so)

My question is: Does anyone know a parameter, that i could tune to get this flag cleared quicker ?

Change the LOG_OPTIONS to log disarmed and post a binary log file.

ok, here’s the log:
I was able to arm twice in PosHold, so GPS appears to be good enough to fly in that mode which requires gps.
After that i activated a fence by aux switch. That brings up the prearm message “fence requires position” and i cannot arm anymore.