S5 won't accept file transfers

[Robert Kemp2]

I haven't added media to my phone in a long while. The OS has been updated a time or two since then. Currently, it's 6.0.1. And there was a factory reset in there somewhere.
Today I connected my phone via USB to my Windows 10 machine, hoping to upload some fresh tunes. Swiping from the top of screen, the USB options came up, but differently from before. Curiously, there was an option to move media from phone to computer, but not vise versa. I tried anyway, but my FLACSquisher app wouldn't allow picking a destination on my SD card. I tried using Windows to do a similar transfer - no luck. I tried another USB cord, I tried restarting the phone, I scoured through the phone menu for options - still no luck. Ultimately, I pulled my SD card out and successfully transferred the files via my card reader, then reinserted the card into my phone - and the files do play.
What's going on that won't allow PC-to-S5 transfers?

 

[wecanfly]

I have a Galaxy S5 (running Lollipop 5.0) and I have never been able to do PC to S5 transfers even with USB debugging on. For me I use a free app called AirDroid and it works just fine. However, I cannot set the file location as my ext SD (I have to move all the files myself). I think it has to do with the Android firmware, but I'm not entirely sure.