Why can't I Sprint in Build Mode using a Controller in Fortnite?

We are aware that our players on controllers cannot Sprint while they are in Build Mode. We are currently investigating the issue.

In the meantime, as a workaround, you can take out your pickaxe/weapon and continue Sprinting. Alternatively, you can unbind Sprint / Autorun (Double Press) under Building section and Sprint / Autorun (Double Press) under Edit section.