When C4D crashes (with or without the help of Corona) and you fire it up again, the Licence Server thinks that you want to enable a second licence and does not activate Corona.
So you have to wait a few minutes to go on and re-enable the Licence.
This is a break in the workflow nobody pays me for!
I don’t think that is expected, but unfortunately we can’t help here regarding the Chaos License Server or the way Chaos licensing works in general. If you have any questions or are experiencing some issues, please contact us using this form https://support.chaos.com/hc/en-us/requests/new so that the dedicated team assists you.