I too had some difficulties getting the first update to work including the "missing" SSID syndrome and here are some things that sorted out my issues
The first time I plugged it in, it shows up as ACORN-XXXXXX. Worth noting the XXXXXX, each new Oak is different. After the first attempt to update, the Oak showed up as an unidentified open WiFi source and wanted me to type in the SSID when I tried to log in. The SSID is ACORN-XXXXXX where the X's are replaced by the last four hex digits of the MAC of the device. If you didn't note this the first time you connected, this can usually be gotten from your wireless router if the device has indeed logged into your router (and you know how to look up your router's client list). It shows up as ESP_XXXXXX in my router list of clients. The MAC address matched the last 6 digits to the SSID numerical part. This is all true and may be interesting but is not the solution.
The solution is to
turn off Windows Firewall to allow the Oak to be recognized as an access point and to once again show up in your WiFu list as ACORN-XXXX with no security ie open. The good news is that it seems to most often disappear when it did update and is blinking its LED in burst of mostly 3. You are either logging back in to try the update again or to tell it how to log onto you LAN/Router legally with full access to the internet (ie what SSID to use and what is the password. I also turned on some wireless permissions to allow connections to open hotspots (WIN10 Settings, WiFi, Manage WiFi Settings). Your antivirus may also block your connection although I did not have to turn off Avast to update.
You have to go back and forth when having issues from internet access to
http://rawgit.com/digistump/OakSoftAP/master/config.html and then switching to the Oak/ACORN-XXXXXX device.
You may benefit from having the OAK fairly near a WiFi source. You can always change the access point/SSID it logs into once it is updated its firmware and connects to the Particle cloud. I had my desktop (could have been my portable) in one room with an access point in it. Strong signals all around. Take your computer and the OAK into the room with the Internet providers wireless router if you don't have a secondary access point to use. A portable in the basement for 10 min is better than 2 hours pulling out your hair. Don't forget to set up your Particle account before you start this...
Now that I have the 1.0 Firmware installed etc., I can talk to my OAK via particle cloud through my basement access point to my upstairs kitchen a few walls away. Haven't pushed it but DigiStump says getting the first update is the hard one and I believe them. Ditch the firewall and possibly antivirus and things go fairly smooth. It is broadcasting -- Windows is blocking since it is an unknown open network w no credentials for your LAN. Turn down the security and it now shows the SSID and things move along as described.
[64 bit Windows 10 Skylake computer, USB WiFi adapter, Wired Internet unplugged, Windows Firewall OFF, Avast On and running; First Update 2 hr, second 10 min. As always, your mileage may vary]
