Tried a third cable and it worked. Looks like I'll need to buy a non-manufacturer cable that works.
I am trying to connect my Galaxy Note 4 to my computer via USB to use SideSync (I know I can still use Wi-fi but it is very slow where I am). The phone just updated to marshmallow, so I was concerned my settings might be off, so I went through and verified that I had USB debugging on (I didn't, but when I changed it, nothing happened).
Debugging is on, and it is set to use MTP when I plug it in. I have tried a different cable (I'm using the manufacturer one, but none work, even other manufacturer cables) and have tried all of the different ports on my computer. When I plug it in, my phone charges, but neither my phone nor my computer recognizes that a device has been plugged in. Nothing appears on my computer at all, and nothing pops up on my phone's status bar.
I have done this successfully before my phone updated to marshmallow (but I may have used an older manufacturer charge cable, not that I think that should matter). I am using Windows 10 and that hasn't changed at all. I can't find anyone with the same problem as me. Can anyone help me out?