Symptom
On Android 11 or newer, your app can't connect to the payment application. Requests produce no response and no error — the binding simply never forms. On Android 10 and below the same code works, which makes this look like a device-specific bug.
Cause
Android 11 introduced package visibility: by default an app cannot see or bind to other apps installed on the device. App2App binds to the Market Pay payment application, so that app must be declared explicitly. Without the declaration, the bind target is invisible and the connection silently fails.
Fix
Add a <queries> element to your AndroidManifest.xml, as a direct child of <manifest>:
<queries>
<package android:name="com.marketpay.pos" />
</queries>
Rebuild and reinstall. The IPC binding will now form on Android 11+.
Verify
After adding it, send a login request — a successful RetailerLoginResponse confirms the binding works. If login still produces nothing, check that a session is actually being established (see Session and login lifecycle) and that the payment application is installed on the device.
Related
- Quickstart — step 2 covers this declaration.
- Troubleshooting: requests are ignored / no response — the other cause of "nothing comes back."