Thanks a lot!
I figured out the structure of the preview build pages. I will try to install the previous versions for now.
To be honest, I did not understand how to use the in_mp3 configuration. As far as I understood, this is the name of a dll library, and it should be configured in a special way to play AAC files. I searched on Google how to do this, but I did not find where to apply this setting.
Actually while I was writing this message I was looking in Preferences window for a proper way to configure the in_mp3 library and found Plug-ins section, and then the in_mp3 plugin in it. So I added ACC to the list of file associations, and now seek/pause in ACC files works fine. On build 1.99.22.20202 without downgrading.
Thanks again for your help!