Hi
I have instaled official TTS mechanism for the Slovene language on Android 12, because Slovene is not on the list of languages in Google's speech services. MIT App Inventor apps work on Android 8 but not on Android 12. I tested the same apps on a similar Thunkable platform and everything is ok there.
Apparently App Inventor is having trouble accessing the other TTS engines (speech API) in Android 12.
If the update has Slovene language, then set your device default to Slovene.
To use Google Text-to-speech on your Android device, go to Settings > Language & Input > Text-to-speech output. Select Google Text-to-speech Engine as your preferred engine. Note, on many Android devices, Google Text-to-Speech is already turned on, but you can update to the latest version
Will it work on Android 12? You will need to try and test and let us know.
Unfortunately, Google does not have the Slovenian language in its speech services, so I have to use other (non Google) TTS engines which work great in other apps, only not in the App Inventor on Android 12. How come?
I am very sorry that I will have to say goodbye to App Inventor, which is a wonderful thing for me, where I learned a lot and created useful apps, and switch to another software tool, but without voice services in my own language, I can't work.
Make sure the TTS you installed is the only one. If I remember correctly, the App will use the Google TTS by default and if not present, the next available.
...the first step towards that is to ask Google to include the Slovenian language. They have Slovenian on the Google Translate website, which is encouraging.
Concerning App Inventor, we need to know which TTS works on Android 12 with Thunkable -note, App Inventor does not yet support Android 12! Thunkable is based on the App Inventor Open Source. They have different demographic targets but the core similarity is there.
... and not only Google Translate, the whole Android is also in Slovenian.
The TTS engine eBralec KSS (app on Google Play), which I use, works on all Android versions for all applications (including Thunkable), except App Inventor on Android higher than 8.
I have requested an update in App Inventor to support the eBralec engine for later Android versions. I'm sure it will happen but currently App Inventor does not officially support Android 12 yet so the enhancement is probably not going to happen very soon.
If you are interested in cultivating grey hair, you could use Android Studio to compile an open-source TTS - which you can customise e.g. delete any unwanted languages.
Do you have a simple app you can share that should trigger the alternative TTS engine but doesn't? We can try and investigate what is happening that would prevent this from working as expected.
The only way is to install the KSS eReader app on Android 12 (it's on Google Play). In the eReader settings you install the TTS engine and select it as the preferred speech engune. You can now run any App Inventor app that contains the TextToSpeech command.