The get request is asynchronous so you need to wait, even .1 or .2 of a second for the first response before sending the next one. Using a loop like this will just fire off 15 get requests so by the time all your variables and labels are updated in the first iteration your loop counter has already sent 5 or 10 more get requests.
I have the same problem. It is frustrating as I am due to launch my app this week, I have been going through hell for the past 2 days. At first, it was Android load that was broke. Then followed by on the Thunkable live. Then a day later, it happened on the iPhone download. And next was the iOS Thunkable live. It was like seeing all my months of effort sinking slowly.
Was there an update to the blocks and some not working now?