altremote_update - cold-start issue

I thought I have solved the issue, but it's still there... before reconfiguration (factory->application) I set the watchdog timer to maximum value (all upper bits 1) and enable the watchdog.

In application mode I created toggling signal (50% duty cycle, 10 us period) to act as a watchdog reset (basically it gets reset every 5 us and the reset strobe stays active for 5 us).

But it doesn't seem to work: my design gets reconfigured after ~3 minutes back to factory image.

Do I have to do anything else when reaching application image except reseting the timer? Is there a minimum distance between 2 timer resets?

I don't understand what I do wrong....