this is not a server problem.
I send you access datas for a site which is using Helix 3 on the same server.
There it is no problem to switch to Helix Ultimate.
It must have to do with the template JSN Venture Pro.
This is not supported since a while and I thought that Helix Ultimate could be a good alternative.
But there are always problems. Since a couple of weeks I try to get a solution with your supporter team. But there is no success yet.
I´d purchased your other templates. But all templates based on Helix Ultimate do not function in this site structure.