I had problems unlocking the bootloader of my Nexus 5! The device was recognized and the folders were visible but was not detected when switched off. So I used "platform-tools" under Linux Mint (because under Windows 10 I have had problems) and, after having opened the folder of platform-tools as administrator, I typed the command lines, but with the smartphone turned on. It was successful unlocked. (Sorry for my English language which is not good)

Is it detected anywhere else? Nexus 5 micro-USB port can be finicky and in my personal experience, it's really hard to have a reliable wired connection with any of my phones so I just gave up and ise wireless connection like SSH as much as possible

@pinetaco Try UT Tweak Tool and use that to check MTP settings and adb while your there(but that should work as you installed UT). Also dev mode is swtched on still. Been along time but I had no issues with N5 and Windows, unless you count cable issues. Should just be a drag and drop or copy paste thing.