When I click on a button that changes values to data, the screen won’t load. However, when I click on live test again it would load the correct results. I cannot seem to find the reason behind this, it worked before but it stopped working.
The way Thunkable handles variables, objects, lists and properties changes pretty regularly and can cause previously working apps to fail on various platforms. Get used to it. 
In the meantime, it is hard to identify the issue from the information you have provided. Can you share images of the start event and open event for the screen that has the problems?