Mouse Controlled Camera Mode Issues Panda3D 1.9.3

In keyboard controlled camera mode, I use a right click to bring up a menu for the clicked object, which works fine, but when I base.enableMouse() a right click responds as if I’ve clicked a very distant object (eg my sky background).
Also the camera movements caused by a left click/drag seem jerky and unpredictable - sometimes the camera flips to an overhead view.
Installing Panda3D 1.9.3 hasn’t helped.
Any thoughts?