@Emil I think I was actually having a similar issue with dash-extensions if I remember correctly (wanted to use the MultiplexerTransform) that went away when I shifted over to vanilla Dash. Both were likely on the latest version as this was two weeks ago, but I’ll try to see if I can create an MRE for you to take a look at some time.
Update: Just saw the post directly beneath this one in my feed about likely the same issue that I faced, so I’ll try out DashBlueprints and see if that solves things. 