I have a similar concern re: how passwords are filled in. I've had LastPass for a number of years now.
Before: When I used to go into the wrench icon for any site I've saved, it would show the original password that I had entered.
Now: When I go into the wrench icon, the original password shows for 1 second, then changes to a default password. This is happening for each site+password that I have saved - it keeps automatically changing to a default password (which is inaccurate for the respective site I'm trying to access)
@User17....9966...I'm sorry that wasn't an answer to your question. I have only seen the "launch" button on my saved sites. The "Launch" button only opens a new tab with respective site. I use the wrench icon to actually see (at least that's how I used to do it) the respective password.
The extension probably isn't seeing any login fields for the page that you're on.