I tested it on one of our installations and it is as I thought: it is the object's fault, or at least the kind of completion settings that the object has doesn't talk well with docebo.
I tried it either with the option "infinite times" and "only until completed/passed".
In both cases, once I finish the object once, I am not able to answer the questions anymore. Next time I open it, it doesn't allow me to go ahead after the first page.
In my opinion this is something that has to do with the completion options that your client set in Captivate. Probably it is in those options that your client has set "you can only take the quiz once" or something like that.
I suggest you to check the above, before going any further into analysis.
But why does it work in 4.0.4? What has changed in 4.0.4 that causes this problem? I was unable to find anything about updated SCORM elements in 4.0.5 besides "Fix: Fixed a possibile issue with scorm player and proxy caching".
As far as I know, nothing....