Yes, same problem for me. TTS engine and radio app can't work. I tried to install others engines, and still same problem. My guess is that HU have a bug in that software version, because on android phone FM radio and TTS engine can work OK. New update of head unit could fix this problem maybe.

Video (Radio app in background, TTS not working, other apps in background, TTS working)
Spoiler: YT video


Other solution on some devices is to set Google-TTS engine as default GPS application. Like that, system could recognize the sound from iGO using Google-TTS engine.

But because that system ignores any TTS engine with Radio app in background, do not know if that trick will work.
For me, no, because system doesn't offer me to set TTS engine as GPS default app, it's not on the list, just other apps but no TTS engine.

Reading this forum I learned that iGO can use internal TTS engine. And with that, tts voice will come from GPS app itself (in this case iGO) and not from Google-TTS.

As far as I understood, I need:
-iGO version that support internal TTS engine
-internal tts engine - tts_nua_ve1
-and propper TTS voice file

I did a quick test on my phone first. I download this TTS voices for wince.
[Only registered and activated users can see links. ]

I use tts_nua_ve1 folder and voice zip.
And it's working on my phone. I'll try that on Head Unit, if this solves the problem with radio app on HU and I guess it should, then it's nice way to fix that problem.

But then I wonder, how can I create or find that internal tts engine tts_nua_ve1 for my language, croatian? My quick test was with english voice.

So far I used VocalizerEx2 TTS engine. From this site I would download croatian language.
Code:
Please Login or Register to see the links
Can I use some files from that download to create tts_nua_ve1 for croatian?
That's what I don't understand, how create tts_nua_ve1 internal engine for your own language?