I've fixed the bug for the next NT5, and 4.38 builds.
However the fix is trivial, so if you are experiencing it you can make the following change.
a) open \clarion6\libsrc\netweb.clw
b) search for
NetWebServerWorker.CreateSelect PROCEDURE
the following line has
ReturnValue String(Net:MaxBinData),Auto
change this to
ReturnValue String(Net:MaxBinData)
cheers
Bruce