This problem has been plaguing me and now it's fixed. When you hover your mouse over the ruler at the top and it turns into a magnifying glass, zooming is easy. It has been getting stuck on the farthest out zoom and requiring a different method to zoom in again. It's fixed now and doesn't get stuck. YAY! 

Good to hear. I have had this problem in the PRV. I will have to check it out

Yes, that's where the problem was. in the PRV