I've been using Motion for about 19 years now... have never had the occasion to use the Reverse behavior...LOL! So, thank you for bringing this up (learn something new every day!)
The documentation for Reverse... sucks.
Reverse works on the timeline from its In point and Out point. Hang on to this. (Same for a lot of behaviors including Overshoot).
In your screen capture, it looks like your project is what? one and a half seconds?
Your Overshoot starts at frame 0 and the Text goes from Scale 0% to Scale 100% (with a single cycle "bounce"). Duplicate this behavior and move it so that its Out Point aligns with the last frame of your project. Add the Reverse behavior but trim it so that the In Point matches the second Overshoot In Point.
With this technique, if you have the "out animation" happening before the last frame of the project, add a Stop behavior to the Text's Scale Parameter and match its In Point to the Out Points of the second Overshoot and Reverse behaviors. The Stop behavior is necessary in this instance because as soon as the Overshoot behavior "ends", the parameter under control reverts to its original setting (before the Overshoot is applied).

(Project frame rate is 60fps and the Play Range is basically randomly set past 240...)
Hope this helps!