Inference line disappears after entering dimension

Why does the purple inference line disappear after entering a dimension?

It also seems that the snap to the horizontal and vertical planes has become much less pronounced after a dimension has been entered. It is really hard to snap to vertical or horizontal after entering a dim.

A couple of other things…

Why when you press enter twice, while sketching, does it not complete the line and continue sketching?

What is the purple line inferencing?

Same here…

Version 5.601.0 (6803)
MacBook Pro M1 OS 14.4.1