The workaround for vMix not having a native way to run a script at startup / profile load has been to have a hidden web browser input that is set to navigate to a vMix web api command
(ex http://127.0.0.1:8088/api/?Function=ScriptStart&Value=scriptname).

I have been using this for quite some time. I just realized it was no longer working on one system. The profile loads but apparently the browser input no longer loaded upon creation, so the web api command never got run.

I can manually reload the browser input and the script runs immediately.

It turns out that if the version is set to anything newer than v86 on the browser input you use to trigger the command, it will not automatically load at startup.

It sure would be nice if the guys would just add a native profile load trigger we could hook to run a script so we don't have to jump through this hoop.

I'm also running 28.0.0.42. This particular machine is one of my older somewhat underpowered workstations so profiles load more slowly on it. Maybe that in combination with the newer browser engines is causing an issue not seen in faster machines.

I wrote some software a while back that uses the same browser framework (cefSharp) that vMix uses for it's inputs and I remember that newer versions didn't run well on lower powered machines.