After rooting- apps on SD card seemingly non-existant
Removing the sd card and SIM, then rooting can do this. It's better to leave them in

This is probably down to the fact that a root upgrade (I.e. Rooting) can change the apps links, meaning a reinstall. I done the same as you, and had to redownload terraria when it was not there but was, and I kept my data. It's kinda like you delete the app, but not the data.