Sounds like a job for the Dashlane. https://support.dashlane.com/hc/en-us Why not use the password manager in the browser? Can you show the issue?

It's wonderful to see your complete submission to Mozilla and, I'm sure they appreciate your immediately placing the blame somewhere else. Testing here with Chrome, DuckDuckGo, Safari, along with Microsoft's browser du jour clearly indicates the only common denominator is Firefox. To be clear this problem only occurs with Firefox after testing against several other browsers. The problem is within Firefox and not Dashlane noting that Firefox recently made change to their browser. Have a nice day.

denniswerskine, if a 3rd party extension or plugin for an application stops working following an update to that application, this doesn't necessarily mean that the application update brought with it an "error" or "bug".

The application may have made a legitimate change that the authors of the add-on now need to code for.

In other words, it certainly can't hurt to also contact the authors of an add-on if it stops being compatible or working correctly with a new Firefox release.

But have you first tried the standard steps of uninstalling then reinstalling the add-on, or testing it in a new profile? (Before uninstalling you may wish to note or export any settings or other user data for that add-on, as these might be removed also)