In the 17.4 RU4 ITIL content installed environment, the new description of the copied tickets are not saved.
Same behavior is noted with text entered with <> ex: <test>, the descripion will be empty. Enter the text as below:
Once the ticket is saved it is empty as below:
Service Desk Manager 17.4 RU2 and above
The issue is happening because missing HTML description related changes in the ITIL content.
As part of the 17.4RU install media, under filestore\ITILContent we are delivering updated htmpl files. This applies as of RU2 and above.
To address this behavior please follow the steps as mentioned in the existing documentation, section "RTE for ITIL content"