Adobe Reader supports nested bookmarks.
Does the problem happen with a particular PDF document?
Acrobat Reader may have encountered an error with the nested bookmarks in your PDF document and could not recover from the error.
Would you be willing to share your PDF document with us (Adobe) so that we can investigate the cause of the problem? If you would like to share your PDF document privately, we can send you the information about how to share it via a forum private message.
Thank you for your help.