Calling Alerts from Watchers to detection Signals

We do currently have threshold rules that might help you out?

But if not your current issue could be that the alert index is not compatible with the ECS (Elastic Common Schema) and then cannot copy over the signal.

Do you have the mapping of the alert index you are trying to create a signal from? I can take a look for you. We have improved the error messaging in our next upcoming release to report more errors transparently to the UI from this release fwiw: