What kind of invisible thread do you use? I use Invisifil and it is wonderful. It is the same size as regulaer thread (not fine like baby hair) and I fill the bobbin with it the same as regular thread. I've never had a problem with it. I used Invisifil to FMQ this table topper.
(Fingers crossed here - this is the first time I have tried to post a picture. Here goes.........)