I found a solution here: https://stackoverflow.com/a/19145783/1607103
I resolved the issue I was experiencing by creating a new dataset and new tables within it. Everything is now working perfectly and data is visible seconds after adding it. I am at a stage in my project where table structures are changing frequently, which seems to be the cause of the issue. I will ensure that modified tables have different names for now.
I am extremely concerned that bigquery is experiencing issues with no visibility. It doesn't fill me with confidence that there are no errors and there is no indication (that I am aware of) that something is going wrong.