Last I checked this is a volunteer forum and sometimes it may take a day or so for someone to see the question and know a possible solution.
Saying that you are keeping the solution to yourself is a prick move likely to not get any help here in the future...
But since you are asking and think you found the solution, I can tell you that you probably haven't...
Lot's of threads on this if you did a search. It is more than likely an issue with your mobile provider.
BI doesn't actually send an SMS. It uses your email to send an SMS text message to you.
As long as the BI log file shows that the email was sent out, it is not a BI issue.
I also suspect that if you look in your email server sent folder, it will show that it sent the SMS message, but since you didn't get the SMS confirms it is not a BI issue.
More than likely, your mobile provider has implemented some sort of spam filter that blocks "auto generated" SMS messages. However, when you push the TEST option, that is a human generated email/text and the mobile provider has some sort of algorithm and analysis that can tell the difference between the TEST that you as a person pushed and an automated alert text.
Sometimes people here calling their mobile provider and complaining magically fixes it. Others have gone to another option like purchasing the BI mobile app and going to push notifications instead, or using another app like pushover as SMS has been getting problematic for some people.
Some have changed their email provider - that helps for awhile, but then it returns.
Sometimes my SMS is fairly instant, and other times it may take days to get it.
So if you are using text messages, at some point it will fail you due to the spam algorithm. Maybe it stops for a few days and returns, or maybe it stops all-together...