brush strokes dissapearing after being made

I've been using Animate for about a year and a half now and have been loveing it! But recently, every time I use the normal brush (B) my strokes dissapear after I lift my pen, they dissapear. No keyframe is made and there are no extra layers. I'm talking about a fresh, new document. It has really put a hold on my creative process and would like some help with solving this problem, PLEASE!!