The new Keyframe editor has severe issues with a Text+ item. I have a very long Text+ item but the editor can only show the first 8 seconds, even if there are keyframes later than that. It also behaves erratic on that 8 sec as well, showing for example the Y position sometimes as two separate lines, both with the same value. The spline view also can't always zoom in even on the 8 sec section, the zoom slider is greyed out.
I also found a topic mentioning about a similar issue on Adjustment clips, so probably related.
Here's a screen capture showing the issue when playing around on a Text+ item: