Clean ACS 4.17.2 install, upgraded to 4.18.1 (automatic systemVM template registration - just "yum update cloudstack-*")
The system VM is (still) correctly marked as 4.17.2 (notice the template says that it's 4.18.1 - all fine)

After destroying the CPVM, it's expected that it will be deployed again from 4.18.1 template, however UI still shows 4.17.2 (the "version" in the "host" table is not updated, is still 4.17.2), while inside the CPVM it confirms it's a 4.18.1 template:


Clicking the "Patch VM" button doesn't change anything (not even with Force)
(in my env, the CPVM is not functional)