MAVFtp issues random crc error which cancels ftp upload

MAVFtp issues random crc error which cancels ftp upload

After downloadin map data using the create_terrain.py script and using MAVFtp to upload this map data to a Matek F765 running arduplane 4.06 beta I get this error:
Exception of type 'Ionic.ZipBadCrcException' was thrown.
at MissionPlanner.Controls.MavFTPUI.<>c_DisplayClass13_0.b_2(IProgressReporterDialogueiprd)
at MissionPlanner.Controls.ProgressReporterDialogue.RunBackgroundOperation(Objecto)

This on Windows 10 using USB 2 and no hub. It happens randomly and if I keep trying the upload eventually MAVFtp will upload the file with no issue.

Is this expected?

Start by reproducing the upload of map data generated by create_terrain.py to the Matek F765, recording when Ionic.ZipBadCrcException occurs. Trace the reported path through MissionPlanner.Controls.MavFTPUI and ProgressReporterDialogue, then compare failed and successful attempts. Done means the random CRC failure is explained and the upload no longer cancels unexpectedly.

Written by the indexing model from the issue text.