Split method has two parameters but shows parameter hints at weird places when indexes are used:

Thanks @vzarytovskii for spotting.
Code for testing/copypasting
open System
open System.Text.RegularExpressions
let regex = Regex.Match("blah", "lah")
let group = regex.Groups[0]
let thisIsFine = group.Value.Split("")
let thisIsWeird = regex.Groups[0].Value.Split("")
let thisIsAlsoWeird = regex.Groups[0].Value.Split("", StringSplitOptions.None)