It's a bug in the Express Scribe software. Express scribe cannot play directly mp3 files so it converts it to wav format. During this conversion process the ending part is eaten. It eats up a certain percentage of the file. If the audio is small in length, then proportionate small portion will be gone and if the audio is lengthy, the a much bigger portion will be gone from the end.
The workaround is to convert the mp3 file to a wav pcm format and then load it to express scribe. It will have the ending portion. Hope the new update will rectify it.