Ways to debug progressive download?

[dogtopus]

I never got the progressive download feature to work properly on one of my own project but I don't know where to start troubleshooting it. Sounds are all muted and every graphic assets are shown with the placeholder appearing first. Asset prediction on that project seems to work fine on regular renpy and only the web version seems to miss everything. Any ideas on what could be wrong or how to troubleshoot it will be appreciated.