I traced it to the wwwebradiobuttonlist::render method in webcontrols.prg (line 2277):
IFLOWER(this.RepeatDirection) = "vertical"this.IsInputControl = .F. lcOutput = "<table " + this.WriteBaseTags() + ">" + CRLFthis.InputControl = .t.
That last line should be
this.IsInputControl = .t.
--stein