I got this situation here. Deployment step as pending forever! Even after the actions were concluded.
I tried lot of things, what solved was to remove all items from Release Template and re add them.
That’s bad how it is, but for some reason Release Management gets lost sometimes with its components.
Here what was blocking me was the rollback component, once I removed the release started going until the end.
Hope it helps you, ‘cause I lost some time investigating that.
Release Management allow us to add the Rollback Always out of the sequence object, and for some mistake it was like that here.
After adding Roolback Always in the Sequence it worked well.
Got the idea to remove some components from here.