Audio sync issues in MimoLive 5

I’m having a issue in MimoLive 5 where my guest using MimoCall are experiencing significant audio sync issues. I’m running a 2018 Macbook Pro, with an Apogee Element Thunderbolt interface. I am on gigbit Internet, and we are streaming to Facebook. So far in my testing, this doesn’t happen with version 4. Any clues as to what might be happening? Any workarounds?