Hi,
Please try "HTTP/HTML request step" on behalf of "REST step" and set the "Host Name:", "Port:", "User:", "Password:" and "Path:"
Then add one post parameter which is suitable JIRA API
Maybe
Key:file
value:@C:/Program Files/CA/DevTest/Projects/CHARMR3_API/Tests/Results/get_hier_01_2018-07-05_negative.html
And change the "Form Encoding:" as "multipart/form-data; boundary=----".
I do not have the access for JIRA and JIRA REST API but I tried REST API in DevTest which would deploy .mar file to VSE and I could deploy the .mar file.
Here is the screenshot of the "HTTP/HTML request step" in my trial.

My trial and this screenshot may help you.
Thank you,