project update hangs forever at TASK [detect roles/requirements.(yml/yaml)]

hello,

project updates (scm git) are hanging very often.
Unfortunately i can’t reproduce this behavior.

it hangs at task:

TASK [detect roles/requirements.(yml/yaml)] ************************************
task path: /tmp/awx_269573_fl2813rp/project/project_update.yml:169

at this task there is no progress until i cancel the job.
Sometimes it works and the project update takes only few seconds.

awx 15.0.1 on k8s

project update uses custom environment with ansible 2.9.5 and python 3.7.4
Enable collections download is disabled.

does anyone know how to debug this behavior or what the problem could be?

thank you and best regards

felix