That’s wild. If it works sometimes, it sounds like you’ve set up Eform correctly.
Hard to say exactly. I would guess it has to do with either your browser cache, or the page’s own cache. You could try un-cacheing the page itself. And the call, too, doing...
When bizarro conditions like that occur, I might also fire up several other browsers to test with, just to have a better chance of getting a fresh start.
Also, if you’ve just changed required fields in your template, there could be a cache lag for awhile.
You’ve also probably noticed that using the same email in the "from" field can cause repeated submission validation errors, so some variation there may help a bit.
Actually, maybe none of this will work, and you’ll need an exorcist.
Good luck, Dave