With the recent iOS update to 15.7.1 or higher and the TD Snap update to 1.24 the speech is not working.
This will happen if you have an iOS voice selected as the Speaking Voice.
How to Fix:
Access the settings menu within the TD Snap app.
Select the Speaking Voice
Scroll through the choices and select an Acapela Voice or a Nuance Voice depending on which is available to you.
Select Done to exit the Settings menu.
Double tap the Home button. This will show the current Apps that are running. Swipe away TD Snap
Select the home button again to view your apps and select TD Snap to launch it.
Test the speaking capabilities by composing a sentence in the message window and pressing it to speak, or selecting the speak button. Also navigate to the quick fires, where the buttons should speak by pressing the button.
If you want the iOS voice to be the chosen voice you may need to download it within the iOS settings.
Open the Settings for the iOS
Select the Accessibility option
Select Voice Over
In the list of voices, find the one you wanted. If there is a cloud with a down pointing arrow to the right, select it.
This will download the IOS voice.
Go back into the settings of TD Snap and select the iOS voice you just downloaded and select it. Test by selecting the speaker icon and verify the voice works.