A major consideration is Qlik Sense platform leverages WebSockets technology (a complete list of Qlik Sense system requirements is available here:
If I am not wrong currently AWS ELB does not support WebSockets and stickiness simultaneously.
It is possible to do some work around, but if you get any problem later, you need to isolate Qlik product environment itself to do troubleshooting and then get support from Qlik Support.
Hope above information helps. Cheers!
One of my team wrote a blog on using AWS ELB for QlikSense
And yes the problem is the ELB doesn't support websockets,
i believe AWS have released an Application Load Balancer (ALB) that does but we haven't had time to test it yet.