If you have checked the UEFI/BIOS settings and they appear to be correct for UEFI-booting, but when you try to UEFI-boot you find that the agFM menu does not appear or when you select an ISO it does not seem to boot (or the USB drive LED flashes for a while and system hangs), or other strange things occur with agFM or Ventoy, then I recommend you reset the BIOS settings.
Go to BIOS Setup menu and find the ‘Exit’ Menu, then choose the ‘Load Default Settings’ option (or similar) and any other ‘default’, reset or Factory settings options you can see.
Then save the changes and reboot back into the BIOS Setup menu and ensure the settings are correct for Legacy and UEFI booting.
USB Legacy: enabled
Fast Boot: disabled
Boot Mode: Legacy (CSM) – if you want Legacy booting
For Secure Boot, I suggest you clear the DBx keys (if possible), or Restore Factory Keys