I'm installing Linux Mint 19.1 Tessa on a computer. I had removed all partitions with Gparted and made a 500MB fat32 partition with flag boot/esp because the hard drive had some problems making the computer not boot properly sometimes. It boots normally now, but when I go to install, it doesn't give me the option to wipe out the disk or anything, going straight to a partition table. This would be fine if it showed the hard drive, but it only shows /dev/sdb under devices, which is the USB I'm live booting with. /dev/sda is only there under "Device for boot loader installation". If I just press "Install now", it says "No root file system is defined. Please correct this from the partitioning menu." /dev/sda is there on Gparted and it says there is 1.82 TB unallocated space.
I made sure to turn off Secure Boot, boot in BIOS mode not UEFI, and turn off "Fast Boot".
EDIT: switched SATA mode to AHCI and tried again with UEFI mode. Didn't work.