For most functions in lua libraries, typing something similar to the name of the function will bring up an autocomplete option and a description of what the function does. This doesn’t happen with string.split
Using string.split :
This happens whenever I put string.split in the script editor and I’ve always had this bug since I found about string.split and started using it.
Roblox has implemented other functions into default lua libraries which work fine with autocomplete. (math.sign, math.clamp)