IBKR is great but they have fucked up before as well. When oil futures went negative early last year, IBKR's software could not handle a negative sign and led to traders not being able to close their positions. Luckily, IBKR took it to the chin and compensated more than $100 million in losses anything their clients owed below $0.

Source: https://www.bloomberg.com/news/articles/2020-05-08/oil-crash...