I really fund a problem, it concerns the automatic login (in the desk program no from 1pwanywhere) of sites i.g. such as duolingo.com and wix.com: it is not working, the program take up the parameters but it does not put it in the login form when the site has recalled from the list.
I think the problem is HTLM5 sites.
I've split your query from the rest of the thread as filling issues relate to a part of the application that we share between Mac and Windows. As such as have a forum specific to it.
Let's start with https://www.duolingo.com We have the same issue with this site as we do https://www.southwest.com. We can fill the login window but something we're doing afterwards is causing the window to hide before it can submit. If you click the Login button again you should find both fields are filled and I'm hoping if you then click the actual Login button you should be logged in. This isn't to say we don't need to determine what the cause of this issue is but hopefully that you can still use 1Password to log you in while you wait for the fix.
With http://www.wix.com/ we have a different issue, one that has bugged me for a while. We don't set the radio button correctly when we fill the page so it doesn't shift from the I'm a new user option. That alone will cause any attempt to submit to fail. This we do need to improve for the obvious reasons. For the moment the only option here would be to set this Login item to not submit after filling. You can do this by editing the Login item and changing the submit option from Submit when enabled to Never submit. This will allow you to change the radio button and then click the login button.
You're quite right, we're not handling either of these sites very well at the moment so we'll have to improve these.
I just wish there had been better news, I much prefer when I can find something that works.