Your comment about the opacity map gave me a lead. The problem could be related to the Dilation parameter of the baking.
The Dilation (also nammed padding) is a process that will dilate the border of your UV islands to avoid certain types of visual issues.

If the Dilation (padding) value is too low, it could result with too "small" islands for the opacity map, turning the pixels near the seams black, so 0% opacity.
My advise would be to make sure the Dilation value from your baking is set to a correct amount and reload your maps inside Substance 3D Designer.
Best regards,
what you mention is not the real problem i will explain what i mean "you know my english is not good but i hope you understand it"
when i you apply a height map on plane the plane border get stretched beased on the height "the border start get wiggly and following the map up and down" and this what happen in my case each cell has its own border and when i inject the opacity mask into height node the border respond to the height map its looks black line becuse the opacity mask uniform white color all over the uv shell when i reduce the black value from the opacity mask i was just reducing the height "as you know pure white full height -pure black full depth" in genral i was trying to achive what i want in wrong way a better why i think still not try it is to use idMAp and try to avoid coloring the border
in the end i hope i slove your problem and i hope you enjoy your substance mister cyril 😄