In an un-customised copy of Sage CRM, a paperclip icon will appear on the CommunicationList to indicate if a communication has attached files.
On amending the sort order options for comm_hasattachment on CommunicationList, the paperclip icon may stop being displayed.
The issue is caused by the GriP_ViewMode field on Custom_Lists being nulled when the comm_hasattachment field is updated on the list.
You can resolve the issue by running the following SQL statement in Management Studio:
set GriP_ViewMode = N'ATTACHMENT'
where GriP_GridName = N'CommunicationList'
and GriP_ColName = N'comm_hasattachments'
Once this is done, you will need to do a metadata refresh under Administration > System > Metadata.
This issue has been reported in v7.1; it cannot be reproduced in v7.2. It will not be fixed in a patch for v7.1. Please use the workaround listed above, should the issue be encountered in that version.