I have a RHEL 6.8 server. I used the redhat solution to convert from UEFI to Legacy (adding an extra step to run in grub native to install into MBR). After the first reboot, everything seemed normal....second reboot, 2 of my 4 partitions come up as unkown devices (pvdisplay or vgdisplay)...i can use kpartx or 'touch' the partion table by running parted and toggling a flag to simulate a change...immediately the disk info returns and is no longer unknown...and shows as /dev/sda4

but as soon as I reboot, it will go back to unknown....

my multpath is also not working properly and will not display my disk using multipath -ll (even when i match a server that is with same config)

I have a feeling its all related but i cant connect the dots.