Unable to indicate rectangle and line dimensions

I am using a tutorial that says to indicate rectangle dimensions you type in 10’,20’ and click enter. I have also used a full stop and semi-colon instead of the comma just in case. Every time I start the rectangle and click from one corner to the next and type in the dimensions my rectangle turns in to a line. When I add a line to a rectangle and indicate the dimensions it disappears. Anybody had this happen to them?

Click and drag the rectangle and then let go of the mouse. Type 10’,10’ and hit the Enter key (do not click).

NOTE: I used 10’,10’ … it works with 10’,20’ as well.

Is there a not displayed but active section plane in your modeling space?

Sounds like you are working in 2d with Parallel Projection so you are only seeing the edge of what you create.