From roundup-devel mailing list:

>> I also tried restoring the status with:
>> 
>>   curl -X PATCH -s -u amin:amin --header \
>>      'if-match: "ff974f63e4ebfba1ecf29aa4cc508c15"'\
>>        '.../rest/data/status/9?@op=action&@action_name=restore'
>> 
>> I got back:
>> 
>>   {
>>     "data": {
>>        "type": "status",
>>        "link": ".../rest/data/status/9",
>>        "id": "9",
>>        "attribute": {}
>>     }
>>   }
>> 
>> but it doesn't show up in rest/data/status.
>> 
>> I finally was able to restore it using roundup-admin.

so looks like there may be an issue here.