I believe that is because you have moved the nodes to fit the view in other places, so when you change view the brush will not fit anymore.
If using RedSDK TC will hide it for you, else you will need to adjust nodes for every view.
To add more node's just select it with Edit tool, keep the cursor over the line and rigthclick, and then select Add Node, or press Ctrl when the cursor is over line and you see a symbol for add or remove a node, click and it's set.
V18, V19, V20, V21, 2015/ 16/ 17/ 18 Pro. Platinum
Deluxe V20, V21, 2015/ 16/ 17
Windows 10 Home Premium 64 bit, 32 GB
NVIDIA Geforce GTX 780m, 1 GB