@olivierlambert Thanks for that information, will use it next time I run into the issue.
Before I read your above reply, I was poking around and noticed that the only SR I had added was disconnected, somehow. So I researched into it and discovered that this was my own doing. Without going into too much detail, I had converted my Active Directory environment from a Zentyal server to a Windows Server and I was hosting the SMB share on the old domain controller. So I had made a DNS error which was causing the SR to not be reachable from the XCP-ng host.
So I deleted the SR and recreated it and viola I was able to create the VM. Honestly, I'm not sure how the two are connected since I'm not storing any disks on this SR; I only use it for ISOs which I mount into the newly created VM to install an OS and then I eject it.
Long story short, my problem is solved but I'm still confused as to how it happened.