we had that problem back in February and got it fixed in March. the techs should be aware of tech tip T-SB-0042-19I am experiencing the same issue on my 2019 platinum LTD.
No voice command only 1200 miles on mine...
I only noticed it was not working because we are on Thanksgiving road trip nav screen shows turns but no audible prompts this is dangerous as I constantly must look at the screen for directions.
Took it in the dealer in Raleigh NC they were great got it working with a reboot ( disconnected the battery) we all believed that was the fix shut the vehicle down and restarted it and no voice command.
A fix I tried is changing the language from English to French give a voice command (phone call prompt etc) and Change it back to English.
It worked but went out for meal got back in my HL tried the nav and NADA no voice command.
I am frustrated as well $45,000 for a top of the line brand new truck and is what we get?
My 2013 limited never give me a bit of headache,not feeling this new Highlander starting to have some buyers remorse.
At least we know it is not an isolated issue.
We are gonna need to make noise about this one it is a serious safety concern from my perspective.
Update:I also discovered the talk to rear passengers system is not working either. Wondering if this is part of or connected to the voice command system...is anyone else having this issue also?