Solder Bridging On SMD Pad for Nexlev Connector

Help Needed.

I face a solder bridging issue on solder mask define pad at edge only for nexlev connector . The pad design such as smd at four corner only. The bridging happen on signal to ground pin only. Current stencil we use 22 round with 6 mils step up for stencil and at the edge we use 20 round with 6 mils step up. So far we already check printing , pick and place and profile as well but don't why the bridging happen at edge on nexlev connector smd only. please help me ...

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