Modern HP systems reserve the key for HP Recovery Manager.
Many HP business systems (EliteBook, ProBook, ZBook) include – a hardware-enforced BIOS protection. If you interrupt boot too many times, Sure Start may restore a factory BIOS image, resetting boot order. This can break Safe Mode attempts. Solution: Enter BIOS (F10) → Security → Sure Start → Temporarily disable during troubleshooting. hp boot safe mode
If you select Safe Mode but the HP system: Modern HP systems reserve the key for HP Recovery Manager