I have the free version and I submit a first PDF file (21MB) which worked perfectly but now I submit a second one (18MB) and it is still running to process the file and the hosting server is now regularly at 100% CPU, saturating... The D Flipbook page mentioned "Please wait! The book is processing for now already 10 minutes...
I let it running hoping it will finalize. Is there any error messages or logfile we can used somewhere to analyze the processing ?