The guys at my LHBS have tried it and are puzzled about what the problem might be. Year before last I brought my whole system over there for a group brew session in the parking lot, and though I didn't brew a weissbier on that day the instructor checked out my setup and didn't see any problems with my process. Besides the instructor, I was the only other AG brewer who turned up that day, everyone else brewing extract batches so he spent most of the time watching me brew.
On a side note, the hefeweizen the instructor brews has the perfect balance of banana-clove and that intangible, elusive German-ness that takes me back to the years we spent living in southern Germany where we fell in love with the style, sipping fresh Hefeweizen in the hot summer sun.
Here are a few things I can think of that I haven't yet tried:
-Another type of fermenter, glass maybe? I ferment 6 gallon batches in 7 gallon plastic fermonsters
-Chilling with something other than my copper counterflow unit
-Higher end malts, I tend to use Avangard though I did a batch a while back with Bestmalz Heidelberg pils. Should I try floor malted Weyermann or something else?
-Intentionally underpitching; I either pitch a fresh activator pack or most recently a pouch of Lallemand MC dry yeast
-Combination underpitching with oxygenation as mentioned by
@TheMadKing
-A different water profile than those listed above
-I own a pH meter but haven't yet started using it, depending mostly on the predictions by brewersfriend
-Due to my BIAB process, most or all break material ends up in the fermenter, should I filter or whirlpool to avoid that?