Arc work Txxxx - not implemented?

We switch to newest arcanist. In our workflow we used arc feature Txxxx as initialization of task work.

Now, with latest arcanist, when we try:

arc work Txxxx
we get following error:

[2020-10-17 11:18:59] EXCEPTION: (Exception) TODO: Implement this workflow. at [<arcanist>/src/work/ArcanistWorkEngine.php:208]
arcanist(head=master, ref.master=4b3baca999a4)
  #0 ArcanistWorkEngine::workOnTask(string) called at [<arcanist>/src/work/ArcanistWorkEngine.php:66]
  #1 ArcanistWorkEngine::execute() called at [<arcanist>/src/workflow/ArcanistWorkWorkflow.php:90]
  #2 ArcanistWorkWorkflow::runWorkflow(PhutilArgumentParser) called at [<arcanist>/src/workflow/ArcanistWorkflow.php:227]
  #3 ArcanistWorkflow::executeWorkflow(PhutilArgumentParser) called at [<arcanist>/src/toolset/ArcanistPhutilWorkflow.php:21]
  #4 ArcanistPhutilWorkflow::execute(PhutilArgumentParser) called at [<arcanist>/src/parser/argument/PhutilArgumentParser.php:492]
  #5 PhutilArgumentParser::parseWorkflowsFull(array) called at [<arcanist>/src/runtime/ArcanistRuntime.php:171]
  #6 ArcanistRuntime::executeCore(array) called at [<arcanist>/src/runtime/ArcanistRuntime.php:37]
  #7 ArcanistRuntime::execute(array) called at [<arcanist>/support/init/init-arcanist.php:6]
  #8 require_once(string) called at [<arcanist>/bin/arc:10]

Of course, it’s possible to do same by using git, but with arc feature it was more convenient, with automatic upstream configuration, etc…

So, question is, am I misunderstanding something or arc work Txxxx is not fully implemented?