WAG?
https://www.urbandictionary.com/define.php?term=wild%20ass%20guess
I added `level` and `num-devices` to all entries in mdadm.conf and
rebooted. It didn't change anything. Manual assembly still freezes the system as well.
hm
(1) are the mods explicitly in the initrd?
(2) can you boot from a usb key with a f39 live-iso and see if the arrays assemble?
if they do, it's likely your config
if they don't, the probs in the array itself (bad metadata, out of sync, etc ...)