Likewise, 696 items in glamour dresser. Also definitely used /isearch just after patch, only encountered this issue after I added a large number of items to the glamour dresser over the past three days, now using /isearch causes a hard exit of the client every time. I also logged onto one of my other characters with an empty dresser and couldn't reproduce.
I went and removed items from the glamour dresser and added them back one at a time, for me /isearch worked normally up to 649 items, and then proceeded to crash again at 650 items. If I removed items again, at 648 items /isearch resumed working without causing a crash, and continued to do so for 649, so this might possibly help other people in the meantime.