Native messaging not working with PPA version but does work with standalone. What gives?

Add-ons Development
#1

I am using 1Password and it has a native messaging component that enables the browser extension to communicate with the desktop application:

$ cat ~/.mozilla/native-messaging-hosts/com.1password.1password.json 
{
  "name": "com.1password.1password",
  "description": "1Password BrowserSupport",
  "path": "/opt/1Password/1Password-BrowserSupport",
  "type": "stdio",
  "allowed_extensions": [
    "{0a75d802-9aed-41e7-8daa-24c067386e82}",
    "{25fc87fa-4d31-4fee-b5c1-c32a7844c063}",
    "{d634138d-c276-4fc8-924b-40a0ea21d284}"
  ]
}

I have installed the standalone (extracted .tar) file version of Firefox to my /shared folder. When that version is running, Firefox calls the 1pass binary per the manifest above:

$ sudo forkstat | grep BrowserSupport
[sudo] password for rsyring: 
18:53:32 clone  183925 parent          /opt/1Password/1Password-BrowserSupport /home/rsyring/.mozilla/native-messaging-hosts/com.1password.1password.json {d634138d-c276-4fc8-924b-40a0ea21d284} 
18:53:32 clone  189746 thread          /opt/1Password/1Password-BrowserSupport /home/rsyring/.mozilla/native-messaging-hosts/com.1password.1password.json {d634138d-c276-4fc8-924b-40a0ea21d284}

I also have installed the PPA version of Firefox from https://launchpad.net/~mozillateam/+archive/ubuntu/ppa. When that version of Firefox runs, the 1Password-BrowserSupport executable is never called.

The versions of Firefox are identical:

$ /usr/bin/firefox --version
Mozilla Firefox 114.0.1

$ /shared/apps/firefox/firefox --version
Mozilla Firefox 114.0.1

Any suggestions on what the problem is and/or how I might go about troubleshooting the problem?

#2

FWIW, also filed a bug report: https://bugzilla.mozilla.org/show_bug.cgi?id=1838978

#3

This turned out to be an AppArmor issue:

[236482.484994] audit: type=1400 audit(1687180387.804:3851): apparmor=“DENIED” operation=“exec” class=“file” profile=“firefox” name="/opt/1Password/1Password-BrowserSupport" pid=1384607 comm=444F4D20576F726B6572 requested_mask=“x” denied_mask=“x” fsuid=1000 ouid=0`

I don’t know if there is something Firefox could do to surface this error and make it more clear what is going on but it would have been helpful to see something in the browser console indicating failures to execute a native messaging binary.