Sprint slide function does not work with the "ALTERNATE" control scheme

It’s a bit tedious but my fix was to make a custom control scheme identical to “alternate” 

The default “custom” is identical to the “default” settings so all you need to do is swap the “crouch” and “melee” and “bayonet charge” options from “b” to “click rs” and then look for “crouch slide” and set it to “click rs” (when it asks to bind the buttons hit “yes”) 

And make sure in the basic gameplay settings that “double tap to slide” is enabled (may be a new feature) this has worked 100% for me so hope it helps