I believe you're being affected by the bug found at JRACLOUD-41675 and JRASERVER-41675. Please review the bug and verify you're affected by that. If so please vote on it to add impact and try the resolution in Images not showing in JIRA email notifications to see if that helps:
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Hello Atlassian Community! I'm Teresa, the Product Marketing Manager for Jira Service Desk Server at Atlassian. I'm excited to announce two exciting releases for Jira Service De...
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