When you Convert a Lead the "New" Button is Missing in the Ticket Tab.
SAP Cloud for Customer
Reproducing the Issue
1. Open the Lead ABC (ABC represents the Lead ID).
2. Check the Status, "Not Converted"
3. Open the Tab Tickets.
4. See the New Button avaible to use.
5. Click in Convert to Opportunity or Convert to Account and Contact.
6. Open the Tab Tickets.
7. The button "New" is not visible.
When the user converts the Lead into an opportunity or account and contact, the internal status changes to Converted, and the Lead cannot be reopened. Once the status Converted is assigned to a Lead, the user cannot modify the Lead, or assign a new status to it.
Once the Lead is converted/closed you can no longer use it.
This is the end life-cycle of the Lead.
This is the expected system behavior.
Knowledge Basic Article - 2679745 - New Button Greyed-Out For Follow-Up Items On Objects Created For Unconverted Leads
Knowledge Basic Article - 2681865 - Leads Converted to Account and Contact Are Locked
Lead, Converted, Locked, Convert to Account and Contact, Action, New, Button, Ticket , KBA , LOD-CRM-LM , Lead Management , How To