When I get testcase using jira.issue(issue_key), I see customfield_11193. There is stored testcase group inside the test plan (extension TestFLO). But when I try to add testcase to Jira using this field, I get error:
Field 'customfield_11193' cannot be set. It is not on the appropriate screen, or unknown.
TestFLO offers the groups inside test plan, and I try to add testcase directly to test group inside test plan. When I do not use that field, issue is added to Jira testplan correctly (but not to the group).