It's specifically about connectivity. Take a look at the V3 product page: MB699VP-B V3_4 Bay 2.5" U.2/U.3 NVMe SSD PCIe 4.0 Mobile Rack Enclosure for External 5.25" Drive Bay (4 x OCuLink SFF-8612 4i)That is ominous… I have already bought it and plugged the drives in, and I do note that some of them felt weird to push in and I’m not certain they are seated correctly despite a few attempts. I have not powered it on yet.
if you are willing to elaborate/explain your comment I’d be very interested to hear. I guess worse case I just have to get rid of it, assuming it won’t cause damage to other components?
It doesn't look too bad now, because everything is solved, but it was a real mess. Both V1 and V2 product pages (they're linked on the V3 page if you're interested) have notes about things that don't work and also refer to the FAQ to check. V3 is the latest version. There is this table "Which ToughArmor MB699VP-B is right for you?" further down on the product page. There are also specific cable recommendations.
There are lots of specifics about this product, about what does and what doesn't work with specific versions in specific combinations.