Marker not Auto-Scrolling when Text Overfills Box

I'm using several markers to break up a long slide, but when I paste in the words for each marker, the scroll bar doesn't automatically appear when the text goes over the allotted space for the marker.  

I need to have each marker at least the same height, but some of these would take up the entire slide with text if I resized each to fit the words.  

I have done this exact thing with no issues within the last 2 months, so I'm not sure why it's not functioning now.

Any thoughts or ideas on how to fix this would be much appreciated. Thank you!