Redmine

I am writing a python script using python-redmine module to automate notifying team about the list of Redmine issues in Design status but Target Version is not yet set in Redmine.

With the help of python-redmine documentation, it was quite easy to read issues and get the issue.status attribute.
Now, for a given issue, I would like to get the Target Version. I am able to list out the supported attributes of a Redmine issue and came to know that Target Version is internally referred as "fixed_version" in Redmine as per the output of

list(redmine.issue.get(1))

I tried to read it via different methods given below.

issue.fixed_version
issue.fixed_version.id
issue.fixed_version_id

But all the above options resulted in

raise exceptions.ResourceAttrError
redminelib.exceptions.ResourceAttrError: Resource doesn't have the requested attribute

So tried the below lines, but it is always returning target_version_set to true.
Can anyone please help me to get the Target Version of a Redmine issue?

My Redmine version is 4.1.0.stable.142, python version is 3.9.5 and python-redmine module version is 2.4.0

redmine = Redmine('http://redmine_url', username='uname', password='pwd')
issues = redmine.issue.filter(project_id=project_id, status_id='open', include='journals', sort='tracker,priority')
for issue in issues:
    #target_version = None
    #target_version = issue.fixed_version
    #target_version = issue.fixed_version.id
    #target_version = issue.fixed_version_id
    issue_details = list(redmine.issue.get(issue.id)) 
    print (issue_details)
    target_version_set = getattr(issue_details,'fixed_version',True)
    print (target_version_set)
    #if issue.status == "Design" and target_version is None
    if issue.status == "Design" and not target_version_set:
           print(f"Target Version is not set for Issue No.", {issue.id})