A blinking light may also mean there is a firmware update for the device.
However, all 3 of your units are not showing up in Airport Utility...
You may have to reset the devices and set them up again.
See this Apple article:
Before you go to the trouble of resetting the AirPort Extreme and Expresses and then setting everything up again.....you might want to try a complete power cycle of the network to see if that will straighten things out.
This is an excellent troubleshooting step and will often solve an issue like this. If you decide to try this:
- Power off / shut down all devices on the network in any order that you want.
- Wait a few minutes
- Power up the modem first and let it run for a full minute by itself
- Power up the next device connected to the modem the same way
- Power up each AiPort Express the same way
- Keep powering up devices one at a time a full minute apart until the entire network is powered back up
Check and see if things are back to normal.