Stimulus Reflex Callbacks stopped working in production

Question

Since I made some updates on my production server and redeployed the application, some of the client-side callbacks and promises between Stimulus Reflex and StimulusJS controllers suddenly stopped working. In development, everything is working fine, in production, just the before callbacks are working.

So, for example, this is working:

beforeReflex (element, reflex) {
    console.log(element)
    console.log(reflex)
    console.log("before")
  }

while this (and others) are not:

afterReflex (element, reflex) {
    console.log("after")
  }

The reflexes itself are working in development AND production, just the callbacks are not in production. I have no errors in the logfile, I have no JS errors in the console, Redis is running and everything else seems to be working.

The serverside callbacks inside the reflex (after_reflex :show_success, only: [:update]) are working aswell.

I can confirm it's not browser related (tested on Chrome, Firefox and Edge).

Could it be an issue that it's a company server behind a firewall? But then the other stuff shouldn't work aswell.

Does anyone have any idea where this could suddenly come from?

I don't know where to search anymore.