after upgrading raspbian to kernel 4.4.13-v7+ custom versions of hostapd are not working anymore as an encrypted access point.
I am just a user and not a developer, but as far as I understand, wifi encryption is not done completely by hostapd itself but relies on some functionality of the kernel. With kernel 4.4.13-v7+ there are problems with hostapd that is compiled with additional drivers.
This topic is discussed in the troubleshooting section of this forum. I am posting now in the raspbian forum because I think help from raspbian developers is more likely to be found here

The issue is discussed here: viewtopic.php?f=28&t=152603
A detailed explanation of this issue can be found here: viewtopic.php?f=28&t=154347
I would be happy to get some information about the interaction between kernel and hostapd and - of course - I would be even more happy to solve this problem. Any help is very appreciated!
Best regards,
Stefan