Delays sometimes get cut off when used in an insert slot of a a track that contains many short audio regions. That means the audio playback suddenly goes silent. Occasionally this also happens with reverb tails.
Since this issue only shows up with very short audio regions, try to use longer regions.
You can convert the short regions, into one long region. To do so, please select all regions of the track and choose:
Region > Merge > Regions.