Trackpad Zoom Problems

Hi, I'm running High Sierra on a 2016 MacBook Pro.

I noticed that zooming on the trackpad, by pinching or double tapping with two fingers, would not work but only on SOME windows.

I had a Safari window opened on the left half on my screen and zooming was working on it.

On the upper right I had another Safari window opened and below it I had a powerpoint opened using Preview, on both these windows zooming with the trackpad would not work.

I then went to the trackpad settings and unchecked the "zoom in or out" and "smart zoom" boxes and checked them again and it seemed to work fix my problem.

My question is, has anyone else experienced this? Is it a known bug? Possibly a one time thing? Any help is appreciated.

Thank you