Same here with Osmand on e-0.7-pie.
Probably because
If you want to stay with Osmand and not switch to
then the only solution I’ve found is to install Google TTS (com.google.android.tts) (anyone dissing me now here, please give me a FOSS alternative first…!).
After installing the TTS you probably have to enable it in settings->system->languages & input->advanced->text-to-speech output->preferred engine.
I then removed any app data usage permissions for Google text-to-speech engine in app settings…