I'm in the same boat as you guys. I got .218 finally with the "Production" ring, but I have been unable to get any build higher than that so far. I've tried every ring (slow, fast, release) with no change (verified in the about screen). I've reset the phone enough times, I've almost memorized the entire setup process and button location that I could do it blindfolded.
I have a feeling that it's either an error on MS side on the update servers, or someone may have found a show stopper error with this phone and MS is holding back the updates till a fix is found. Personally I think it's the first one.
FYI for anyone else, just wanting to get to .218 from WP8.1 here are the steps I used to finally get to it.
1. Register as an Insider (insider.microsoft.com) if you haven't already done it.
2. Make sure you have a backup image of your phone on your OneDrive account.
3. Download the "Windows Device Recovery Tool" (aka WDRT) (
http://windows.microsoft.com/en-us/windows-10/windows-device-recovery-tool-faq) to make sure you get the newest firmware and WP8.1 SP2 (for some unknown reason my phone never got the newest firmware on it's own, but was able to get WP8.1 SP2).
4. Run the WDRT, you may have to manually select which phone you have as it doesn't always find the Blu Win HD LTE. Follow the on screen instructions.
5. Setup your phone and select the proper restore image.
6. Verify your phone and apps are updated.
7. Download the Upgrade Advisor from the app store and run it to get WM10 .164
8. Verify that all updates for the phone and apps have been installed after you get WM10
9. Download the Windows Insider app from the store.
10. Run the Insider app and select the slow ring, and let the phone reboot on it's own.
11. After reboot, go check for OS updates (it will most likely say you are current).
12. Run the insider app and now select "Production" (yes it says to "Stop Insider Preview Builds"), follow the prompts and let the phone reboot again.
13. After reboot, wait a bit, then go check for OS updates. It
should find an update that will bring you to .218