Can't upgrade to AccountRight Pro?

Hello,

I just started using MYOB 2 days ago and am getting to know the software.

I started a trial for a simple "MYOB Business Lite" version, which is the lowest level version I could see advertised (screenshot attached).

Today, I thought I should take a look at a higher level version, so I tried to upgrade my trial to the "MYOB Business AccountRight Plus" level that I saw on the pricing screen.  But for some reason, it doesn't let me upgrade to that level. The highest plan I can choose is the "MYOB Business Pro" account type.

What is the reason for this? Can you not move between different plans?

I am suspicious that this might mean MYOB isn't a single product, but a patchwork mess of different products. That's usually what it means. The risk is that it might mean an expensive migration activity to move between products, which is an absolute deal breaker from my perspective. No other accounting software works like that, unless it's going out of business...

From a customer perspective when you see a Pricing Plans page like the one below, you assume that the software will scale as you grow, allowing you to move up to each level of "Plan" as your business expands and you need new features to support you. So before I get too far into my trial, I want to know whether this is the case, or if there are major barrier points to scaling up.

Am I right? Is MYOB a patchwork mess of products?