Now I'm getting it, and I can see two parts of the problem. That device you have, which is said to be a Fan Hub, is NOT. It is a different device called a SPLITTER. A Splitter merely connects all its fans in parallel to the host header on the mobo, and hence ALL of the fan electrical power must come from the mobo header. All such headers have a limit on power available, typically 1.0 A max. Most current simple fans draw from 0.10 to 0.25 A max each, and you have SIX fans. So that alone says it is entirely possible that your system is trying to use too much power from a single fan header. A real fan HUB does it differently and works only with 4-pin fans. What it really different about a HUB, though, is that it has an extra "arm" that must plug into a SATA or Molex power output connector from the PSU to give the Hub (and all its fans) more power than any header can do. You do NOT have one of those.
Next is a subtle detail of the fans. I see the case says it includes "6 Halo Single-Ring Blue LED Fans". It does NOT say RGB Fans, or some such. I expect each fan has ONE cable from it that plugs into a fan header, and NO other cable. That is called a LED Fan, an earlier version of lighted fans. In it, the LED's added to the frame are normally all ONE colour and are simply connected in parallel with the motor for electrical power. This increases the power requirement of each fan to the range of 0.35 to 0.50 A each. It also means that there is NO way to connect the fan lights to a mobo RGB or ARGB lighting header for power and control of them separate from the motor. Thus no utility like RGB Fusion can do anything for the lights.
So, those six fans connected that way are overloading the mobo fan header you have used, and its power output to the fans fails. When that happens, BOTH the fan speed AND the light brightness fail. That is what you are seeing.
So, what to do? You need a different way to connect six fans. Further, which way depends on the fan motor type. Does the cable from each fan end in a connector with THREE holes, or FOUR? The answer tells us how the fan speeds can be controlled, and hence what device to use. Next, tell us the maker and exact model number of your mobo. We need to look up its detailed specs for how many fan headers of which type you have to use, because it is VERY likely you will need to use more than one for those six fans.
Lastly, IF you can find a label on a fan hub, tell us what it says about electrical power. I'm sure it will say 12 VDC. But then what does it say about Amps or Watts?