Why transitioning an issue via the rest api clear the description?

[Alaric Calmette]

Hello!
I'm using the rest API to transition issues after a deployment. 

I'm making a POST request on :

/rest/api/3/issue/<issue_id>/transitions

With this body :

{ 
    "transition" :
        {
            "id": <transition_id>
        }
}

 
The transition is correctly done, however, the description field of the transitioned issue is cleared afterwards.

It's not because of a post-function in the transition, there's none.

Does anyone knows why the description is cleared?

[Lucas Rolfes]

I was originally seeing this with my trial setup, but it appears to be working. This is with the most recent JIRA and Bitbucket cloud hosting, so it may be an older version issue?