If Auvidea already says only one port works, then it’s likely only one port works.
It sounds like you are coming to this with mis-matched expectations.
Welcome to the world of industrial research and development!
$258, for a product they may be selling perhaps a hundred copies of, is not bad at all. And I would expect it to not be perfect.
If you try to compare to finished products built for end users to use, made by the hundreds of thousands, of course the prices will seem “steep.” It’s not the chips that cost, it’s the work to develop the boards, and when you can spread that work over a hundred thousand, it’s cheap; when you spread it over a hundred, it’s much more expensive.
If you try to compare to, say, the Arduino ecosystem, then the Arduino is based on 30 year old technology, old-school 5V or 3.3V chips, and very sloppy timing requirements, because it’s such a limited microcontroller. A talented first-year EE student could bang out a working Arduino as a class assignment, so the amount of “development” there is somewhat less than for a board that needs to support gigabit-level differential signalling pairs for busses like PCI-Express, HDMI, USB 3, and MIPI. Similarly, the software stack for an Arduino is a few dozen files; the stack for the Linux kernel is thousands of files, many of which the developers need to learn and understand to properly integrate a new system like this.