I have this problem from time to time where trying to seed a cluster from a tile fails.
Sometimes it will seem to work okay, with two blue faces showing the chain of communication, but then one face will turn off and eventually the first tile will get into a fail state.
I’ve tried it in the dark in case ambient light was causing a problem, but it doesn’t help. Any ideas?
Aaand it started working again after I rearranged the cluster 
I’d say something interfering with the link between the 2nd and 3rd blinks in this video. The game transmision protocol will only try 3 times to send a packet and then give up and move on to the next face - as is seen here. It is less forgiving than most games that will send continuously so the data still gets through on a marginal link (although only with sporadic updates).
Could be slightly bad alignment between those two faces, marginal IR LED on either side, a spec of crud on either lens, etc. Any of those seem plausible here?
Maybe use the IR tester sketch on those same faces and play around to see if you can find any pattern or clues?
In my experience, everything @bigjosh says do cause this issue and the issue itself is somewhat common. Whenever that happens the first thing I do is to rearrange the Blinks and that sort things like 99% of the time.
Getting this quite often. I tried rearranging the cluster, attaching to different faces on the dev Blink and the cluster Blink. I’ve found if I switch back to my older dev kit Blink - the one with the pins - it works consistently. Obviously it’s not as convenient since I need to insert/remove the battery each time. I’ll play around with it more.
Maybe you have a scratch in the lens of the dev Blink?