I have the same issue, but I don't think this is a Adobe Lightroom issue. It seems to be more of an Imagely plugin issue. Did you try posting a support issue on the Imagely support site?
I've had this too. I've worked with it extensively trying to make it work, checking & double checking login details, setting up dummy wordpress sites both locally and on remote servers.
I've submitted support requests but the best I seem to be able to get from Imagely is a link to the troubleshooting page, which is of no help whatsoever. My conclusion is that it's broken.
I now have a working, if primitive, publish plugin of my own that publishes at twice the speed of the Imagely one, is easier to set up and fixes some shortcomings of the Imagely plugin. I'm working on the logistics of making it available. I should know more in a week or so when I've thoroughly tested it.
To date, I'm not that impressed with Imagely's support.
Yes, I have reached to Imagely as well and they basically copy and pasted some generic response back to me. Most of the items they mentioned I had already checked and indicated in the initial email. I have yet to get a follow-up response.
I would be happy to test out any alpha/beta versions of your plugin. I am a developer by profession, so I would be happy to help in anyway I can. Just not well-versed in Lua unfortunately.
I'm just figuring out Lua compiling. I'll make something available once I'm there. KYP.
If you'd like to give it a crack, Ngg++: A Lightroom Publishing Service for NextGen Galleries. | Buggering About in a Small Land
I've been using it for a week or so and, other than one oddity that's proving stubborn, it's working well. That said, there's a lot of ifs and buts in the release pipeline. In particular, it's not been tested on Windows, Mac only. Although I've looked fairly carefully for platform gotchas, it's still untried.
It's currently twice as fast as the Imagely plugin and 3 times faster than the AlloyPhoto one.
Let me know how you get on, shout about problems. And good luck.