The column will cut the wall for the extent of the column. In the second case the column might either be not joined to the wall (which means it wont cut it) or the column may not extend to the same bottom and top constraints

This is an old stupid behavior that i observed with out of box concrete columns. The bad aspect start to show when you put concrete beams between concrete columns or sometimes(didn`t tested to much) when you attach columns to a roof. Anyway the bad part is that you can`t repair them by joining in order to cut the wall again. You have to delete them and replace with new instances or eaven with new instances of similar familes but with some parameters adjusted (always export as geometry unchecked and show family pre-cut in plan views checked). Anyway eaven with this settings sometimes it`s not working becouse the behaviors were discretly changed between 2009 2010 2011 versions.

The fast solution is to use the atached insteed (tested only in 2011...). I use them and i forgot about this problems . The column is an 2009 updated version but this doesn`t matter. If i used a newer version i observed problems some time. The beam is posted by someone else (i don`t remember) and it has the zero gap between column and beam.

Do you have, by any chance, moved the wall around causing it to disjoin? It could also be this before mentioned bug. I've seen this happen in projects on some occasions, but it stopped after I started using my own columns and beams.

yes i have moved the walls .. . Let me try creating columns & beams