Anyway, the issue that I encountered is that ironically if you do not specify a non-zero "Days To Add" value and just supply one of the other parameters, the calculation will not work. That is, if we were to specify parameters in the screenshot above (where we're trying to add years to the date) it would not work.
Luckily there is a simple workaround solution. Below is the same function call except we trick it by subtracting a day value and then cancel it out by passing in the equivalent days in the week parameter.
If you needed to use the week parameter, then you could similarly pass in 24 hours and cancel it out by passing -1 to the day parameter.