Hi Charlie @KingFisher78 ,
Here, again, it is (almost certainly) not a difference in Blender Version.
What happened? I can’t tell from just a description (I’d have to see the .blend file, probably, to be able to figure it out).
One thing, that will affect the Smoothing, is not just the Angle you set, but also the Angles in your Model; if you for instance used a Cylinder with a different Amount of Vertices, then the Smooth Angle Threshold would be different as well. For instance, with 8 Vertices, the Angle would be 45 (360/8) and with 12 Vertices, the Angle would be 30 (360/12).
I can highly recommend watching Modify and use it as reference to go back to whenever you need to, but especially watch the Bevel Modifer Lesson: https://cgcookie.com/lessons/lesson-2-bevel-modifier
That’s not only the Modifier that trips ‘beginners’ (and I use that word in a very broad sense here) up the most, but Paul also explains very well how the Edge Angle (that is the angle between the Faces, connected to an Edge, while Face Angle is the angle between Edges of a Face. That’s what you get, when you let programmers do the naming 😉) is being calculated in Blender; this also helps to understand the working of the Smooth By Angle Modifier.
