I’m doing my development on macOS. The Linux I have available, is a headless server without DE, nor X11 or any other form of UI. I exclusively use the terminal version of Joplin on Linux.
Therefore my knowledge of the dev environment on Linux for the desktop and mobile apps is basically non-existent.
But there might be similarities which could help in narrowing down this problem.
When I start react-native run-android, all components are started automatically: the compile run, the metro server, the emulator. In the past, I had to start the emulator manually.
I’m missing the output where it tells you which emulator is used. Did you start the emulator by yourself?
At the end you should see something like this:
> Task :app:installDebug
04:46:38 V/ddms: execute: running am get-config
04:46:40 V/ddms: execute 'am get-config' on 'emulator-5554' : EOF hit. Read: -1
04:46:40 V/ddms: execute: returning
Installing APK 'app-debug.apk' on 'Nexus_5X_API_29_x86(AVD) - 10' for app:debug
04:46:40 D/app-debug.apk: Uploading app-debug.apk onto device 'emulator-5554'
04:46:41 D/Device: Uploading file onto device 'emulator-5554'
04:46:41 D/ddms: Reading file permision of /Users/tessus/data/work/joplin/ReactNativeClient/android/app/build/outputs/apk/debug/app-debug.apk as: rw-r--r--
04:46:42 V/ddms: execute: running pm install -r -t "/data/local/tmp/app-debug.apk"
04:46:44 V/ddms: execute 'pm install -r -t "/data/local/tmp/app-debug.apk"' on 'emulator-5554' : EOF hit. Read: -1
04:46:44 V/ddms: execute: returning
04:46:44 V/ddms: execute: running rm "/data/local/tmp/app-debug.apk"
04:46:45 V/ddms: execute 'rm "/data/local/tmp/app-debug.apk"' on 'emulator-5554' : EOF hit. Read: -1
04:46:45 V/ddms: execute: returning
Installed on 1 device.
Deprecated Gradle features were used in this build, making it incompatible with Gradle 6.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/5.5/userguide/command_line_interface.html#sec:command_line_warnings
BUILD SUCCESSFUL in 34s
317 actionable tasks: 13 executed, 304 up-to-date
info Connecting to the development server...
8081
info Starting the app on "emulator-5554"...
Starting: Intent { cmp=net.cozic.joplin/.MainActivity }
What is your output?