Answer

Device icons in Q-Sys Designer's Configurator screen may appear to "flash" or alternate between blue and green if there is a QSD (Q-SYS Discovery) conflict.  

This is most likely because IGMP Snooping is configured within the network switch(es), but you've also enabled a Hard Link in the Designer Preferences for the same device(s).  Hard Links are only to be used when either multicast discovery traffic cannot traverse the network.  With IGMP Snooping properly configured there is no need for Hard Links, and in fact these two functions (Hard Links and IGMP Snooping) will tend to "fight" each other.  

Either disable the unnecessary Hard Link(s), or disable IGMP Snooping in your switch(es).