Autofill doesn't work at boardgamearena.com on iPadOS

I'm using 1Password on an iPad, running iPadOS Version 18.6.2, and the Chrome browser.

Autofill works fine for most websites. When I tap in the username or password field, I get a prompt at the bottom of the screen to autofill my credentials from 1Password. When I tap that prompt, I can unlock 1Password and autofill.

But this doesn't work at boardgamearena.com (https://en.boardgamearena.com/account). When I tap in the "Email or username" field, the 1Password prompt does not appear. If I tap again, I get options for "Paste" or "Autofill," and if I tap "Autofill," I get options for "Contact" or "Passwords." If I tap "Passwords," the OS says, "AutoFill Unavailable. The developer of "1Password" needs to update it to work with this feature. You can open "1Password" to copy information to fill."

What's especially confusing is that autofill works fine for this same website on other devices (Windows, Android). And as I mentioned, it works fine for other websites on iPadOS. So it's only the combination of iPadOS + this specific website that is broken.

Can anyone help me understand why 1Password doesn't work in this case? Is there a setting I can adjust to fix it?