iirc all the common cbu fuses had radar altimeter in falcon too and they would burst according to agl not asl.
I got problem but only with rockeyes. Other cluster munitions seems to works fine but these just hit ground without triggering in Jugoslavia mountains with ad:2 and ba:2800. Target was at 3500 ft above sea level and I dropped those from 14000ft.
With other clusters I can set ba to 500ft and those still explode no matter of target height from sea.