gviliunas

After more tinkering, I discovered that the problem with using v3.9 LiFX bulbs is not PG3. The problem is with using a devlist.yml file. With previous revisions of bulb FW, the bulb MAC that the router associates with an IP and the bulb SN that the PG3 devlist contains were the same. Now, with firmware 3.9, the MAC address is different from the bulb SN.
Here is how to use LiFX bulbs and a devlist if you have any bulbs with firmware version 3.90:
1. Add LiFX bulbs to your WIFI network. Find the bulb's MAC and IP in your router's status pages. Configure your router to issue a static lease to the bulb(s) so that the IPs will remain constant. Note the IPs and MAC addresses of your bulb(s). (See example screenshot)
2. Configure the LiFX Node server to NOT use a devlist. Restart the Node server and let it automatically discover all of your bulbs. You may need to click "Re-Discover Bulbs" several times.
3. In the Admin Console, look through the status pages of each bulb discovered. At the top of the page will be the bulb's name with the Node server slot-number and bulb SN listed below. (See example screenshot)
4. For each bulb, compare the SN  obtained in step-4 with the MAC obtained in step-1. If the bulb firmware is 3.90, you will find that the MAC and SN differ by 1. In my example case, the MAC is d0:73:d5:3f:2a:e7 while the SN is d073d53f2ae6
5. To build a devlist.yml file that will work, for each bulb, use the IP address from step-1 (In my case 192.168.1.58) and the SN (formatted with the colons:   d0:73:d5:3f:2a:e6) from step-4. Install the new devlist.yml file. Be sure to add the location of the file on the Node server configuration page. Restart the Node server.
All of your bulbs should now be working.
Many thanks to @xKingand @einstein.42for their work in developing this very useful Node server and porting it to PG3!