Google Play Books doesn't work when displaying subchapters in index

[Talayero]

Hi,
I'm using Google Play Books very satisfactorily to read epubs loaded in my Energy pro reader.

I'm using an older version, 3.4.9, following the good advices of SteveAdams, Purple Lady and other members of this forum.

The only problem I have is when I try to use the index of an epub that has subchapters. When i touch the dropdown menu to see and access to the subchapters, Google Play Books stops working.

I'm afraid there may not be solution for that.
For the moment, what I'm doing is changing the level of the chapters in those "problematic" epubs using Sigil, and reloading them in My Books, but that's quite a job, because I have a lot of epubs with subchapters.

I would appreciate very much some help or commentary.
Thank you in advance.