Truncated document properties > subject/description

I'm using Javascript to generate pdf files with repetitive metadata, such as subject/description. I'm doing this by importing as xmp file as data object and replacing certain words or strings, then assigning the result to doc.metadata. I have been doing it this way for 4-5 years.

I currently have a longish description that used to be accepted whole before and now gets cut off. This happens somewhow *after* I save the file.

docNew.metadata = xmpContents; //string from xmp file
var sTitle = "Some title";
docNew.info.Title = sTitle;
docNew.saveAs (...)
console.println(docNew.metadata);

Console shows me that after saving the file and before closing it, subject/description is complete, but when I close and open it again, it is cut off. The same thing happens when I paste the value manually in Document Properties.

Has some char limit been introduced regarding subject/description length?

Thank you for your help!