The full error:
dw_savelist : d_qt_savelist_organisation Row changed between retrieve and update.
No changes made to database.
Delete from "Savelist_entry" Where "Savelist_entry_ref" = ? r
Error while deleting row 29
Database error number is : -3
This indicates that since you entered the Saved List, either a record has been deleted and the pending changes cannot be saved to that individual or a GDPR process has been run against them.
The best steps to follow would be to Refresh the list (unfortunately this would lose your progress) which will bring the recent changes into your list.