There are breaking changes to the firmware between v0.6.2 to v0.8.0-rc.9. You should review the changelog. Specifically, there are changes to Particle.publish(). I don’t see anything about Particle.function() in the changelog. The SOS fault codes say that 7 blinks is an “Exit”. @bko wrote that post, maybe he has insight.
There are multiple discussion about Photons having intermittent connection especially after a period of time such as this, this and this. Some of the issues were lengthy delays in code.
Without seeing any code whatsoever, we can only speculate. I assume you are not using Web IDE so would it be possible to post to github?