I don´t think we can fix it but anyway.
I did export the book in all the formats (The book is empty, just the defaul information after the creation)
Because maybe my server is slow (the cheap one) the files need too much time of difference between the first format and the last one (it could be the same problem with a good server but too long books). Because the time of exporting is different, split the files to be in two sections. Now it need 2 batches for one export.
In other hand, to extend the time for being inside of one batches will join two exportings, and that is a problem as you can see.
Other problem is the time of the exportings. The wordpress default time is the London time, but the export of the files show -2 hours. I´m in spain, now is +2. The time of the exports is my time - 2 hours. Take a look the screeshot, is from now and here is 17:17.