Ran into similar problem with Z6 G4 when installing W10 or W11 at 22H2 with November 2023 BIOS. Issue turned out to be lack of boot driver in the current Microsoft build for the sSATA features in the Z6 G4. Solution was to download the SP relative to the model and serial number from HP, extract to a second USB key and install driver when asked during the Windows set up. The driver was automatically selected when I ticked the "only show drivers relative to this computer" check box. Evidence was that the drive was shown as present in the BIOS but no partitions were shown in the "select where to install" panel during Windows Setup. There is a "install driver" box at the bottom of that Setup window - and then browse to the USB key holding the extracted drivers. Note that this fix worked when the BIOS was reset to factory settings and with no other changes than the order of booting to the USB key that held the Windows source. Apparently this issue is showing up in other recent computers.