Well, I have the similar problem. I tried the "Add phone number" menu and tried the "Setup 2FA" on Twitch settings menu but it didn't work because I didn't receive any verification code on my SMS, even I tried to change SIM card to another phone it didn't work, and please I don't have any phone numbers blocked, my device has sufficient signal and receiving SMS from other services, and never used “Do Not Disturb” mode, as Twitch Support said. I'm not sure this is Twitch problem or maybe region problem, and please once again, STOP promoting Authy because I don't want it.
Well, I have the similar problem. I tried the "Add phone number" menu and tried the "Setup 2FA" on Twitch settings menu but it didn't work because I didn't receive any verification code on my SMS, even I tried to change SIM card to another phone it didn't work, and please I don't have any phone numbers blocked, my device has sufficient signal and receiving SMS from other services, and never used “Do Not Disturb” mode, as Twitch Support said. I'm not sure this is Twitch problem or maybe region problem, and please once again, STOP promoting Authy because I don't want it.