Biobakery conda install: can't run example data

Dear developers,
I posted on github, but got directed to this page.
I’m trying to install on a HPC:

  • OS: Oracle Linux (Red Hat) 8.6
  • installation method: conda create -y -p ${TARGETDIR} -c conda-forge -c bioconda -c biobakery "biobakery_workflows=3.0.0a7"
  • postinstall: I downloaded kneaddata databases with kneaddata_database command

I tried to execute with the example data form this repository:

biobakery_workflows wmgx \
        --input biobakery_workflows/examples/wmgx/paired \
        --output outdir \

but always I get this error:

Traceback (most recent call last):
  File "/apps/biobakery-workflows/3.0.0a7/bin/", line 184, in <module>
  File "/apps/biobakery-workflows/3.0.0a7/lib/python3.9/site-packages/anadama2/", line 800, in go
  File "/apps/biobakery-workflows/3.0.0a7/lib/python3.9/site-packages/anadama2/", line 141, in run_tasks
  File "/apps/biobakery-workflows/3.0.0a7/lib/python3.9/site-packages/anadama2/", line 884, in _handle_task_started
  File "/apps/biobakery-workflows/3.0.0a7/lib/python3.9/site-packages/anadama2/", line 196, in task_started
  File "/apps/biobakery-workflows/3.0.0a7/lib/python3.9/site-packages/anadama2/", line 641, in task_started
    self.log_event("ready and waiting for resources", task_no, self._daginfo(task_no))
  File "/apps/biobakery-workflows/3.0.0a7/lib/python3.9/site-packages/anadama2/", line 597, in _daginfo
    return msg.format(len(parents), parents, len(children), children)
TypeError: object of type 'dict_keyiterator' has no len()

I don’t know how to troubleshoot. Any direction, hint or idea would be welcome.
I couldn’t find any related issues here, on the anadama2 github page or the biobakery forum