I think it started after I encrypted partition and then interrupted the process and deleted it.
After that I made some other actions, but unfortunately I can't remember the exact sequence.
As a result, now, when I try to encrypt another partition I get warning "You had scheduled encryption ..."
However, when I click on "Resume interrupted proccess" I get message that "You don't have interrupted".
So, VeraCrypt sends contradictory messages.
Also, I do not remember that VeraCrypt urged me to finish encryption process right after reboot.
Also, when VeraCrypt shows the warning about unfinished encryption it does not show the list of unfinished disks/partitions.
All of this does not increase confidence and actually it makes fill that VeraCrypt can resume encrypting wrong place and corrupt some data.
I am sure that it is possible to show the list of interrupted disks. You can simply add an unencrypted header that will contain information on whether disk/volume is fully or partially encrypted.