App in failed status

I have one app in my version 2 rack which is in failed status.
convox apps -r prod

content-collector-g2 failed RJYIIULKWAM

In the last release promote, helthcheck faild,
the reason was because the first thing the app do is a call to an external server that was responding error 500 and if this call failed the app can’t start .
The old containers where running fortunatly, but with a less number of container than requested by scaling properties.
After a day the external server starts to work again, and the app returned to work with the same number of container requested by the scaling properties.

Now the app is in faild state but is running .
If I try to promote a new release with
convox releases promote RCZACGSDCKL -a content-collector-g2 -r prod
the response is
Waiting for app to be ready…
and stay stuck

also a rollback does not work (with convox app cancel content-colletor-g2 -r prod)

how can I return with running state for this app ?
Thanks in advance
Regards, Paolo