You’re correct that there is a known problem with GE bulbs where they may lose connection with the network, but not usually a bunch of them at once. Still, it can happen that the one that goes bad is at a critical point where it is acting as a repeater for the others so sometimes you might see four of them all get lost once even though it’s really only one that is demonstrating the symptoms. This problem is the reason why the GE bulbs Are not on the official “works with SmartThings” list.
On the other hand, that shouldn’t have affected the motion sensors, and several people have reported having weird issues with Zigbee devices. Actually this has been going on since March.
So, I’m going to give you two suggestions. One of these is just the standard thing you do with any zigbee network that is acting goofy. The second is the link to the FAQ for GE bulbs that go offline.
However, if neither of those work, report it to support because it may be something specific to SmartThings.
1. Heal the zigbee network
Healing a zigbee network is easy. 
Just take the smartthings hub off of power for at least 15 minutes while leaving all the other Zigbee devices turned on. Take out the batteries from the hub if it has any as well.
The zigbee sensors and bulbs will all go into “panic mode” as they realize the Coordinator (the smartthings hub) is not available.
Then when you put the hub back on power, each individual zigbee device will rebuild its own neighbor tables. It can take a while for this process to finish, so you may not see improvements until the next day.
A fortunate secondary effect of the hub being offline for 15 minutes is that it will then re-sync with your cloud account.
2. Ge bulbs FAQ
Because of the known GE issue, you may have to also do some resets on individual GE bulbs. See the FAQ.
3. Contact support
If one and two don’t fix the problem by the next day, contact support. But at least know that you are not alone.