I used a kickstart file with the command
clearpart --all --initlabel to make sure anaconda would clear any disks before trying to create and format new partitions.
This has worked in the past for me, on physical machines. However, when doing so on a KVM guest with an underlying LVM volume as storage, Anaconda waits for user input at the following warning:
I'm going to answer this question myself. I mistakenly thought my problem and solution were related to this question here on ServerFault. Since they are not, I'm creating and answering a new question.