JS Error after updating to 9.3 (Subtract from Variable)

Dear all, since I updated to v9.3 (6343) a few days ago I keep getting an error messages from my browser when I use the "Subtract from Variable" action in a course. Since this action is included in our template it applies for around 40 courses. Before the update there was no problem at all with this issue. Details on the error: After publishing to scorm or html my browser tells me that there is an error on the current page. This message tells me that "Object does not support this property or method" and points on the following line in the html site:

function action20841(fn){

 Varpagetmp.sub2('1');

 if(fn) eval(fn);

}

When looking at the course in Lectora preview it runs fluently. When I run it in html or scorm with DEBUG mode the whole communication stops after the course fires the "Subtract from Variable" action. I also tried it from another PC (also updated to v9.3) which gives me the same error.

Since it only appears after publishing I assume it is some kind of JS error regarding this substract method. Are there known problems with this kind of actions since 9.3? Anyone has an idea what else I could try?

EDIT: I just tried to publish it on a very old installation (v2008 SP2 (5609)) and there is works perfectly fine.

Regards, Stefan