The button code for the radius bend needs to be different from the button code of the square bend.
Right now the node where you left the radius bend has the same code as the node where you erased the radius bend. When you refilled, both nodes still have the same code and they will both fill with the same bend - you just changed it from radius to square (made square bend the default).
If the square bend is the default to be used by design line, then place the radius bend button code at nodes where a radius bend is desired.
If the radius bend is the default to be used by design line, then place the square bend button code at nodes where a square bend is desired.
To place a button code, select the button of the desired fitting and then select the node(s) where you want the fitting.