Me too. Then I called Samsung to see if there was something that could be done and they just told me to keep waiting for the update to be released. It's only been 6 months.
It's June 2nd. Am I the only person with an unlocked s9 that is still on the Google January security update? This is absurd.
It is a T-Mobile problem. Just put in a sim that is not t-mobile, and you will get the latest July 2019 update. Any sim from AT&T, Verizon, Sprint, and so on... After update, put your t-mobile back.
As an update to my original post: after chatting with Samsung tech support and them sending me to a local Samsung service center, (ubreakifix) who tried unsuccessfully to use some kind of "fancy" factory data restore, I ended up with a phone I had to reinstall everything on and yet I was still at the January security update--plus they said, it must be your motherboard then and we'll have to replace it. I called TMobile and their Tech support rep assured me, "after talking to other reps" that it must be a problem with Samsung and that there was nothing they could do and that they had never even heard of the problem. So, eventually, after waiting months with no update from January 1 on T-Mobile, I got a sprint sim and put it in. Within seconds, it found the latest upgrade and is updating my phone to the June Security update as I type. And then immediately updated me to the July security update. Yay! It is true, put in another carriers sim and it will update your S9! Though, what the heck, Tmobile?! How come every other carrier can make these updates available to unlocked S9 phones and you can't. Not only that, you can't get off your behinds to be honest with your loyal customers and help them out.