When clients , Matters or Employees disappear from the system when doing an import (usually with Monimp32), and yet the records are clearly in the import file it is probably the case that there are some inconsistent settings being used.
Using AutoImportMarkAllTerminated = 1 or the check box in import "Mark all records terminated before importing replacement" is set, then AutoImportReplaceEntry must be set to 1.
Failure to do this, means that Import will first mark all records terminated, and then proceed to import only the new records, rejecting replacement records, since they already exist.
This has been fixed in Version 2.8 Pre-release vii onwards for Monimp32, which reads these settings from the PABX.INI file. Specifically setting AutoImportMarkAllTerminated = 1 will cause Monimp32 to read AutoImportReplaceEntry=1 regardless of the setting in the PABX.INI file.