Thank you so much for the quick feedback.
But still the problem is not solved.
I'm pretty sure it's an RSO related issue. When I start a new game, I found the following message.
"The resource fermium-ore is not configured in RSO. It won't be spawned!"
I've made a request to RSO, but I don't know when it will be confirmed and resolved.
It's a pity, but I'll try to enjoy the mod without fermium ore.
Will it proceed without mining fermium ore?