ade 4.5.10 doesn't add new books downloads at android tablet

Hello,

I have digital addition 4.5.10 installed on iconia acer android tablet for a few month now.  Was working all right so far.

Suddenly, it  stopped function properly.  Currently it has 2 serious issues:

1.  new book (downloaded on pc and transferred to android) is not in the library anymore.  when android tablet  is connected to pc, I could see: they are there.  but they disappear when I open ade on tablet.

or 2. if I downloaded more than 1 book, digital edition doesn't open at all.  after I delete new additions, ade opens again. 

How to fix that?

Thank you in advance. 

Inna