I have been using Silverblue 32 on my mid-2015 vintage MacBook Pro Retina edition (15" screen). I initially had this set up with two EFI partitions - one for macOS, the other for Silverblue. After running rpm-ostree update past 32.20200702.0, the Silverblue partition failed to reboot. Worse, I could not recover via GRUB, selecting the prior kernel, and doing an rpm-ostree rollback.
I reported this to Red Hat Bugzilla [1]. It appears that there is a Github issue on the Fedora CoreOS issue tracker that may be related where this is happening on HP and Lenovo models [2].
[1] 1855116 – Unable to reboot AND rollback after upgrade to 32.20200702.0 on MacBook Pro
[2] "System BootOrder not found. Initializing defaults" can be worked around with "Boot from file" · Issue #563 · coreos/fedora-coreos-tracker · GitHub