As I said - Demy A3 is on opener + disable. All she is doing is buff extending. The heal is irrelevant since nobody is taking damage, and the debuff duration reduction is irrelevant since nobody is being debuffed. Similarly, Sandlashed does nothing special beyond just buff extending, since her passive will never trigger. Having a 3rd buff extender doesn't help, since Wix already does that job.
One thing I did notice is that Geomancer passive might be helping a fair amount. 15% damage reduction is nothing to sneeze at. You could try running him on the team, or possibly someone like Venomage with a similar passive. Or even someone like Helicath or Roshcard for block damage, to make the shields take less damage.
Can you share your stats on Wix and Brogni? Who is in the shield set?
I have Wix in the shield set and I wonder if that could impact the results?
This does not seem like changing champs. It feels like something basic in the builds of Wix and Brogni. Everything that I read or watch says that with Wix and Brogni its a no brainer team to build.