Unless you base is in the plains or the mountains something is very wrong.
Unless they changed it.

And I don't think they should be replacing base raids. They should only happen away from base in plains or mountains.

Do you mod your game? Wonder if it is a mod issue?
They are RNG so not getting them vs getting them can be hard to judge but the base thing really has me wondering if something is wrong with the game.

Have you tried to verify your game files? With game shut down...
Library
right click game name for Properties
Local Files
Verify