On WaveLab 11.1 eLicenser-Edition (and below?) - Test with WaveLab 9 Pro … this does not happen.
If one edits the labels (temp-Label) and plays the audio while doing so … If the play-curser comes across the edited but not yet saved marker, the edited text (in progress) is deleted (and replaced with what was saved for the marker).
If only the markers are changed and “store markers only in a separate file” is set, not only the marker file is written quickly but the whole audio-file (very slowly and not necessary).