Hi, this case could be related to Alin005 problem and add more information:
I've got here a client's PC with Gigabyte H410M H V3 (Rev. 1.3) motherboard, with BIOS upgraded to version FC, downloaded from here
https://www.gigabyte.com/ar/Motherboard/H410M-H-V3-rev-11-13/support#support-dl-bios
Intel Core i3-10100 CPU 3.60Ghz, 8GB RAM
It has Windows 10 Pro 64-bit 21H2 installed.
With only the onboard video it works fine, BIOS output shows duplicated both through the VGA and HDMI conectors, when Windows 10 loads, it extends the desktop through both conectors (being the VGA one the main screen by default).
When I add a PCI express card, it doesn't shows any BIOS output on any connector from either on board and PCI express card, while after booting Windows 10, it can show the four desktops two connected to the onboard video and two on the PCI express card.
So that confirms a lot of things: working bus, slot, card, unconflicting coexistence of onboard video and expansion card, and a inconvenience to show the UEFI BIOS post and Setup. I tested some settings on the BIOS, including defaults, and could not make them to show. Could it be a bug on the BIOS/mb? While I tested with three graphic cards, I must admit they are old, and posible the BIOS has compatibility requirements, although I didn't find information about this.