Verified for EL7 and FIPS mode that the disk is encrypted when the client is kicked and the disk is automatically decrypted upon boot.
Had trouble on EL7 when the client was not booted into FIPS mode. The disk was encrypted, but did not automatically decrypt upon boot. I solved the problem by uncommenting out https://github.com/simp/simp-core/blob/master/build/distributions/CentOS/7/x86_64/DVD/ks/pupclient_x86_64.cfg#L249-L257 (contrary to the instructions in the file).
Bug entered and PR made to address the problem.