This appears to be caused by the partitioning on the target install disk. In the UbiquityPartman.txt log-file it shows towards the end there are 3 primary and 4 logical partitions, which means the disk label is MSDOS not GPT.
Looking further there is no EFI System Partition on /dev/sda.
Therefore the problem here is that the Ubuntu installer was booted by the PC in UEFI mode. You need to change that by selecting Legacy/BIOS/CSM boot of the Ubuntu installer at boot-time.
If Ubuntu installer boots in BIOS mode this problem will not occur.
This appears to be caused by the partitioning on the target install disk. In the UbiquityPartman.txt log-file it shows towards the end there are 3 primary and 4 logical partitions, which means the disk label is MSDOS not GPT.
Looking further there is no EFI System Partition on /dev/sda.
Therefore the problem here is that the Ubuntu installer was booted by the PC in UEFI mode. You need to change that by selecting Legacy/BIOS/CSM boot of the Ubuntu installer at boot-time.
If Ubuntu installer boots in BIOS mode this problem will not occur.