Ubuntu 18.04.3-LTS installation alongside Windows 10 cannot detect Windows 10

While attempting Ubuntu installation from an USB image, I get stuck because Ubuntu cannot detect my Windows installation.

My system specs are as follows:

1) Desktop with Intel 64 bit Family Core(TM) i3-4150 CPU @3.50GHz   2) Two MBR partition of hard disk with 100 GB and 500 GB free space, besides a small system reserved partition.  

I have already done the following, mainly following from solutions in How do I install Ubuntu alongside a pre-installed Windows with UEFI?

1) Disabled Hibernate and fast boot. "powercfg /a" says only Standby (S3) available. Further I shutdown with -f -t 0 option 2) checked that Confirm-SecureBootUEFI gives cmdlet error, implying system does not support Secure Boot. 3) enabled legacy only as well as legacy first in the Boot options.