Could you try uninstalling the LastPass extension then reinstalling from here https://lastpass.com/download/ to see if it resolves this issue? If not, could you try adding a site entry using the Save All Entered Data feature?
I am having the same issue and it's a pretty big deal as we use this in our organization. Creating and sharing new accounts on the fly like this was the selling feature we were looking for but after trying everything we could to get this fixed it simply is not working. So frustrating!
I see that you are a LastPass Teams subscriber, which includes phone support. So that we can resolve this issue as soon as possible, could you reach out to the Support team via phone to investigate and fix this for you? You can access our Teams support number through your LastPass Admin Console > Support.