Regarding the logs, there is a current issue with those (in the UI anyway). So logs won’t be showing up there:
That may be affecting the CLI too now.
As regards seeing the cause of the failure … if your release shows you a vm id at any point (the easy place to get that is the logs, but, well …) an alternative way to get at that would be to look at one’s status:
fly vm status [id here]
… and that may show issues/errors to show what went wrong. However it too may be affected if logging in general is not being output. Not sure how intertwined those two are.