virtualbox.org

I have been using VirtualBox on multiple machines (Windows 8.1 laptop, Windows 7 desktop) as a vm for an Arch Linux guest. After upgrading to 5.0+, I am experiencing an issue with what I assume is something to do with the resolution or scaling of the guest. I'm not 100% sure how to describe it, so I've attached two pictures that hopefully illustrate the issue I'm seeing (sorry they're a little blurry, I provide better pictures once my 1 day, 1 post limitation is removed):

Pre 5.0: Post 5.0:
I have played with the Scaling Factor in settings, but even though this does let me get back up to a similar scale as what's seen in the Pre-5.0 picture, the workspace no longer fits without the vm window (i.e. I have to scroll left/right to get the whole view of my linux desktop)

Downgrading VirtualBox and the associated guest utilities does indeed fix this, but that's not a long term solution.

I assume there must be a setting somewhere that I'm missing, that I didn't have to (for whatever reason) deal with before. I just don't know where to look.

I'm not sure what information I need to provide, so please let me know.

Current system information:
VirtualBox 5.0.10 r104061
virtualbox-guest-utils 5.0.8-2
4.2.5-1-ARCH

As mentioned, this is an issue on both my Windows 8.1 laptop and Windows 7 desktop. It's a larger issue on my laptop, due to my laptop being 3200 x 1800 resolution (vs. 1920 x 1080 on my desktop). I have tried manually changing the resolution within the vm, but this doesn't lead to a solution (ends up causing blurry fonts, etc.).

I can also confirm that all the virtualbox utilities are running:
Other details:

I get different behavior based on how I have the view settings set. Under View there is the option to "Auto-Resize Guest Display" - if I have this set to True, I get the incredibly small scale that seen in the picture above. If I have "Auto Resize Guest Display" turned off, however, when I reboot the machine and start Xserver the guest display is in a tiny box in the center of the window. If I go into Scaled Mode the font is now very large. This is apparently due to the resolution being set to 640x480. If I then go into view and set Virtual Screen to be as large as possible (it goes up to 1920 x 1200, which is not the max resolution of the laptop monitor) the guest display resizes to be a bit larger and when I go into Scaled Mode the scaling looks closer to what it should be, but it is still not correct (everything is still too small).

Not sure if those are relevant details. Not sure where I should be looking next