I think part of the problem is that the front may be pretty shallow initially, which means that, by the time a surface parcel reaches it's LFC, it's been lifted and advected 10-15 mi behind the front. This may explain why we see persistent development immediately behind the front. Unfortunately, the front continues to chug sotheastward at 10-15 mph, while the storms are moving primarily northeastward or NNEward, which isn't allowing any of them to move into the true surface warm-sector. The storms that did develop in the warm sector (near the DFW metroplex) have fallen apart in the past hour or so.