Need to reboot Android to see new files After recording with Field Recorder, I connect my Lenovo S6000L via USB to my PC. However, the newly recorded audio files in WAV format are not visible until I reboot the tablet. Android version is 4.2.2.

Is that likely an OS or an app issue? Can I avoid the lengthy reboot?
It's a bug in the app. Android has a thing called the media-scanner, which scans newly added files for metadata, so they can be included in media players, photo albums, etc. It relies on the app that creates the file signalling the media scanner process to scan the new file. If the app doesn't do this, the new file won't be added/visible.

If you look at other questions with the media-scanner tag, you'll see some ways to force a full re-scan, at the cost of draining the battery somewhat.