Communication is to the hue bridge. ( for technical reasons, the Phillips hue device is a “bridge,” not a “hub,” hence the name. )
What you’re seeing is called a “popcorn effect.” It may even be that the last couple are timing out.
Easiest way to avoid this is to set up a scene through the Phillips hue app and then activate that scene from SmartThings. The hue bridge will do a group cast to the devices which should reduce the popcorn effect and prevent any messages to individual bulbs being lost.
There’s no way to trigger Hue scenes in the official SmartThings features, but you can do them with core or with IFTTT.
IFTTT is simpler to set up, but may have a little more lag.
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