Try an iPhone hard reset
I just got a set of the Logitech G fits earbuds and was running into the same problem that other reviewers have noted. I could not get the lights to flash quickly, I could not get any connection to my iPhone. Finally, I did three things that might’ve helped. First was to let the earbuds charge in the case for about an hour and a half. Second was to delete the app from my iPhone. Third was to do a hard reset of the iPhone. Once I had done those three things I re-downloaded the app and tried again. This time it worked exactly as described. Fast flashing lights, easy connection, and then I molded the tips to my ears. Still only three stars for a rating because that’s a lot of things to do just to get it to work.