Can't draw on my maps for some reason?

I am selecting the drawing tool with a solid color, and I'm on the tokens layer. In fact, I've tried it on all layers to no avail. For some reason, I cannot use the freehand drawing tool in any of the games where I am the GM. In games where I'm a player, I can use the brush just fine! My players have also confirmed that when I am drawing (as GM), they don't see anything on their end. This has been a recurring issue for about a month or two. Before this, I had always been able to use the tool. Any ideas?

For clarity, I will add that I can use the Pen/Line, Rectangle, and Ellipse tools just fine. This only happens with the Freehand brush. 

The only thing that comes to mind for me is .... Freehand tool is meant to be disabled on the Dynamic Lighting layer. It's not good to use freehand for DL Walls, it's better to use Pen tool there. I don't know if yours is somehow stuck, from being on the Light layer earlier? It sounds like you have made sure that you selected the tool when using other layers?  Are you on a supported browser type, Chrome or Firefox with extensions disabled?  Try it again with the Fill color selected as-well-as the line color? Just to see if it's only your Line that is invisible, or the fill too?