Hey Reena,
We ran into this same problem a few weeks back. Turns out the Sony A7S II can shoot AVCHD footage in the X-AVC-s codec, which is currently unsupported by Sony’s AMA plugin for all the sony formats. We converted the AVCHD files into Quicktime ProRes LT files through Adobe Media Encoder. The new converted quicktime .mov files AMA linked and transcoded without any problems.