I only got the idea because of my kernel image was not showing up in my output when running grub-mkconfig the first time. I thought maybe there is something wrong with your kernel image why it hangs trying to load/find the root partition and that reinstalling the kernel might fix it for you as well, since the problem sounded very similar even though not quite the same. So it seems reinstalling the kernel triggers something more than what is triggered when just running dracut-rebuild.
I’m glad you have a working grub setup now! 