Picoscope 5444B, Tested on Picoscope 188.8.131.52 and Picoscope 184.108.40.206 (Beta)
If the trigger is fired while zooming is active, then only the section of waveform currently zoomed to is shown correctly. If you change the zoom window, or close the zoom window then the waveform display is incomplete. If/When the trigger fires again, the the output is corrected. Please see the attached document which has screenshots.
This is really only an issue for DUTs which generate infrequent triggers. So far as I can see a frequent trigger quickly obviates the issue.