Hello Aussie and welcome to the ArtRage forums 
I’m not sure from your description but my first thought was that it sounds a bit like you have possibly set Smoothing to too high a value.
What happens if you lower it to say 5% or 0%?
It might also be worth noting here that any tool can be set back to it’s basic default settings by left clicking in the area at the top of the Tool Settings Panel, where the tool icon and preset name are displayed. From the popup menu choose Default Settings.
And if you have altered setting in an existing Preset, and want to get back to the Preset you started with, just re-select that Preset from the Presets Panel.
Maker Of Replica Macoys
Techie Stuff:
ArtRage 6.1.1 ~ 15" Macbook Pro ~ macOS 10.14.6 ~ 4 Core i7 3.1GHz CPU ~ 16GB RAM ~ Wacom Intuos4 M