Why is there no liaison for the second person singular, that is, as between e.g. 'aies' and 'été' in 'que tu aies été'?
Is it a peculiarity of the second person singular?
Or is there some more general principle, of which this phenomenon is an application?
For 'être' see: https://www.youtube.com/watch?v=vIjoHatxZt8
For 'avoir' see: https://www.youtube.com/watch?v=8x7RCaQMopk
The pattern seems fairly consistent. For conditional passé of 'avoir' there is liaison for every person and number except for the second person singular.