I found a fix for my problem. Apparently FFXIV doesn't like the default settings under "Adjust desktop size and position" in NVIDIA settings. Mine was set to No scaling, Perform scaling on: Display. It should look like below.

https://i.imgur.com/D4ZiWQJ.jpg

I happened to just try this setting after attempting to run the Stormblood benchmark as a test run and it kept giving me an error saying that "A screensize of at least 1024 x 720 is required to run". I went to look for that issue and someone suggested to turn off DPI scaling, which didn't help, so gave the above a try and it worked.