I’d say the most probable cause for this behavior (from what already was asked and said above) is your new MB’s bios configured to boot from UEFI devices with legacy boot disabled (as pointed by @twohot). Fedora Live DVD is able to boot in both modes – so it works. If your Fedora 30 installation was done in a legacy (non-UEFI) mode, it can’t be booted in UEFI mode – and so bios doesn’t see it.
The option on ASUS motherboards is usually called Launch CMS, you need to set this to enabled, and please check the submenu there if any. And it should be in the Boot section of bios settings. If you still can’t find it, i’ll recheck my own for more detailed instructions.
If the legacy boot is enabled already, try setting Secure boot to “Other OSes” or maybe even to “Disabled”. It’s usually right next to Launch CMS option. I think “Other OSes” should be sufficient. I’m 100% sure I’ve booted my Fedora machines with Secure boot enabled (and even set to “Windows blah-blah” mode, the strictest one.
Then again, if you’re planning on using some proprietary / additional drivers for devices – such as NVidia GPUs or some WiFis – you can just as well disable Secure boot right away, it’ll interfere with such drivers.
P.S. From my experience having latest or older bios shouldn’t affect visibility of boot devices. It’s still a good idea to have it updated, as BIOS updates can contain some bugfixes, performance and even security fixes.