Having the same issue, was surprised at how silent my rig was performing after resuming from sleep, just to find out that iCUE was completely laggy and wouldn't fetch sensor data off my AIO, GPU, CPU and fans.
You have to manually restart their CorsairService for it to work again, either in services.msc or in iCUE under General...
I'm reverting back to v4 until they fix this since I use sleep a lot.