Adobe cookie has a maximum file size of 4KB. This limits us to about 12 documents with offline access at a time (also depending on the length of the watermark as that is stored within the cookie as well). When the cookie space is filled, it cannot add any more entry to the space so that is why offline days were not being honored for newer documents.
When the cookie space is cleared then the users will once again be able to save offline access to documents.
In Adobe Reader/Acrobat 10.1.1+ on Windows, Adobe has increased the maximum cookie size more than 4KB. Preliminary testing shows it can handle 80 documents and more without worrying about overfilling the cookie space. This means that your Users who are using Adobe 10.1.1 will likely not encounter any issue.