Known issues with Jira Service Management
Avoid unwanted removal of Assets fields in Customer Portal
When you request a request type in the Customer Portal, Jira Service Desk runs an integrity check. If you don't have Assets or any third party plugin custom fields, the added fields are automatically be removed from the request types. Compared to the Jira agent view where fields are only hidden, in the Customer Portal the fields are be completely removed. This might be a Jira Service Desk issue.
Only update Assets in a "maintenance window" with a proxy rejecting request to Jira. Don't use Jira Service Desk without Assets installed if you don't want the Assets fields to automatically be removed.
You can track this issue here: https://jira.atlassian.com/browse/JSDSERVER-5474