Photon reverting to listening mode

I just received my last production of 50 units with particle photons.
I’m using version 0.6.0

I have 2 boards where I program the wifi credentials and leave the test application running and the particle photon “loose” the wifi settigs and goes back in listen mode after a moment…

Then I do:
particle serial identify
Particke keys doctor
particle keys server
Reload the wifi credentials and reload firmware and it work fine… but did that again…

Any ideas?

An other one did that too…

Does your code use WiFi.setCredentials(), WiFi.clearCredentials(), WiFi.listen() or any flash write instructions that might be executed unintentionally?

BTW, what do these three dots stand for?
What happens after Listening Mode?
Is it really l
Listening Mode or could it be breathing blue (as opposed to blinking blue)?

The only thing I do is
EEPROM.put(EEPROM.length() - 10, count);
Every like 30 seconds to 1 minute to save the number of test cycle.

three other devices this morning…