When in a project, you can add a task by clicking 'New Task' at the top left of the task list, or 'Add More Tasks' at the bottom left of the task list. The one up top opens a modal, the one at the bottom is much more useful bc it allows you to add tasks in-line. This is especially helpful when using a custom view to add your new task easily, filling in the view columns left to right.
Apparently, this bottom option disappears if your task sort is not sequential. Based on different use cases, we don't use sequential ordering for tasks but rather a view column. It makes no sense that this adding task option goes away if you change the sort. Please keep this showing at all times, WF!