If changing a bios setting from legacy to UEFI changes your result, it is (almost) certainly not a driver issue.
Filesystems like NTFS / FAT / HFS sit at a higher level than you need to troubleshoot just yet.
If any boot disk (USB or not) is not detected when the motherboard firmware is set to UEFI instead of legacy mode, this is a partition table issue. Note I say partition table, not partition.
The partition table contains partitions, and it is entirely possible you've deleted all the partitions on the USB device, leaving an effectively empty partition table. The partition table is still going to be there however, and if it is an MBR (Master Boot Record) partition table, then you need to replace it with a GPT (GUID Partition Table) partition table.
An MBR partition table is a legacy format partition table that you computer will just not see unless the firmware has legacy support enabled.
Legacy OSs require legacy partition table formats, but you mention Windows 8, which has full UEFI / GPT support, so this shouldn't be an issue.
More info:
GPT: https://en.wikipedia.org/wiki/GUID_Partition_Table
MBR: https://en.wikipedia.org/wiki/Master_boot_record
Using Microsoft's approach to convert an MBR disk to GPT:
https://technet.microsoft.com/en-gb/library/dn336946.aspx
There is some technically incorrect (though very common) usage of terms in the MS page, but that may help if that's your background. Feel free to use comments to ask for details if needed
note added by barlop
There were some good corrections to the ms link, david posted the corrections in comment, unfortunately a moderator deleted them rather than moving them into a chat link. I'll include here what I recall from memory what I recall David saying.
The MS link uses the term partition style, the correct term is partition format.
The MS link states that MBR has a 4TB limit, this is incorrect as there is a way to go beyond that with MBR. Perhaps David can edit some details back in, but I see some discussion here http://serverfault.com/questions/590524/why-are-there-only-four-primary-partitions-on-an-mbr-diskhttps://serverfault.com/questions/590524/why-are-there-only-four-primary-partitions-on-an-mbr-disk The MS link also says it's difficult to go beyond 4 partitions, that's not correct. You can have multiple logical partitions(as another Ms link says clearly and as is well known). The MBR limit is 4 primary partitions as that serverfault link says.
There may have been other things he mentioned but I don't recall..
