I be having the same issue.

Yeah me too! The "device not found" issue is persistent! 

Here I am with a newly built custom desktop. Constructed not by me yet, EVGA Flow Control doesn't work.  I don't know which header the AIO pump is connected to on my ASUS motherboard.  I do know it is not connected to the four-pin AIO header.  The wiring was installed so neatly; I am not ready to undo it.
I have been reading the various forums on this subject and am always interested in finding a fix.  The CCVI device was not showing though I finally corrected this, yet I still get the CPUWB device not found.  I might add, I read in one of the many forum posts about this and am successfully using another manufactures software.  I now can assign RGB color, and all case fans and CLC 240 are operating.  I am maintaining suitable CPU temperatures.  Intel I9.  Average 33-40C with no complex processing.  Even then, I have only seen 55C.  So I would think the AIO pump is working.
 
I will watch the forum, yet this issue has been ongoing for quite a few years.  

Today, I was able to get the flow control software to actually get past the CPUWB device not found.  Yet this only happens with versions 2.02 and 2.0.03.  I didn't find much use for it.  All newer versions would not load the device.  Too much time was spent for so little in return.

... Still an issue in July 2023. Flow control stops with an CPUWB not found windows error message upon waking up. Sucks but i may ditch my CLC 280. I can't remember to check if it's on every time i wake it up. 

Yes, there were in July of 2023.  I gave up back in 2021 with this.  All I need is to know my liquid temp and, no doubt, my CPU.  NZXT  CAM does that for me.  I thought about ditching my CLC 240, yet it is doing the job it is intended for.  So until it starts failing, I will keep it in place.  Software is a crapshoot.  The same goes for RGB.    

This is embarrassing:  I was looking at my 360mm cooler and realized the USB may not have been all the way in. I had to push extremely hard and sure enough it snapped into the WB.  Been 2 years of using that cooler and watching it occasionally turn red when running Boinc CPU tasks.  The flow control is finally working!
 
Z400, Windows 11 23h2 (thanks HP)
 

BeemerBiker
This is embarrassing:  I was looking at my 360mm cooler and realized the USB may not have been all the way in. I had to push extremely hard and sure enough it snapped into the WB.  Been 2 years of using that cooler and watching it occasionally turn red when running Boinc CPU tasks.  The flow control is finally working!
 
Z400, Windows 11 23h2 (thanks HP)
 

Excellent troubleshooting. Glad that is solved for you.