Booting from USB device

I have a hooks file to hotplug a USB device at the prepare stage. Using OVMF version 2.6 this works fine, but using OVMF 2.7 the guest no longer boots from the USB device. Option 1) For it to work I have to set the boot order on the USB device and once the OVMF Shell appears I can reset it and it will find the USB device and boot. Option 2) Another setup which works if I remove all boot order settings from the guest and have a boot dev = 'fd' and this works every time.but I cannot add multiple entries. <os> <type arch='x86_64' machine='pc-q35-5.1'>hvm</type> <loader readonly='yes' type='pflash'>/usr/share/qemu/ovmf-x64/OVMF_CODE-pure-efi-tpm.fd</loader> <nvram>/etc/libvirt/qemu/nvram/b96bfc99-3612-0daa-9d8c-69e9d550d05a_VARS-pure-efi-tpm.fd</nvram> <boot dev='fd'/> <boot dev='hd'/> Any thoughts on how to get option 1) to working without having to do a reset.