While sketching a bit the pen stops working (will not draw – like out of ink), and the mode selection – erase, pencil, marker etc cannot used (stuck in pencil mode).
I can use the mouse to select the menu items successfully, but not the drawing/eraser modes at top left of drawing paper with either mouse or pen. oddly, I can click on the tools with the mouse or pen and they move (downward) slightly, but do not change the selection (pen tool remains highlighted). I can also use the floating tool bar to select any of the tools (they highlight) but they do not change the tool selection.
iMac 2012 27″
Wacom Cintiq 16″
AP v5 Alpha 3