Open & Fill from the Firefox extension sends me to an incorrect Vanguard login page

I have a login item defined with website https://investor.vanguard.com.  The 1Password extensions for Safari and Chrome log me in correctly to the Vanguard Personal Investor site. The Firefox extension tries to log me in to the Institutional Investor site instlogon.vanguard.com.  Changing the autofill behavior from "Fill anywhere" to "Only fill on this exact host" makes no difference.

MacOS 26.7

Firefox 156.0.1

1Password 8.12.36

1Password for Firefox 8.12.32.33 (Latest available)

1Password for Chrome 8.12.37.1

1Password for Safari 8.12.37.1