Check your cables. Not all cables can carry the voltage and longer cables have sufficient voltage loss that a monitor won’t power on. DisplayPort has standards for stability and a LOT of stuff on the market is trash. Check the DisplayPort website for registered and supported vendors for their 1.2 standard.
I was thinking the same thing. A lot of times your standard Menards/Walmart/Best Buy/eBay stuff won’t do the job. I can’t tell you how many cables I’ve trashed because I either bought the wrong kind or they were simply garbage.
This is not a cable issue. The same cables work fine using the hub off my laptop.