Some vertices aren't visible when i go to edit mode from weight paint mode When I am in weight paint mode and I want to create a vertex mask. I click tab and some of the mesh does not show the vertices.

I can hit alt-h to unhide but when i go back to weight paint mode and the vertex paint, it wont let me paint over them or show the vertices. how can i unhide those vertices? I'm fairly sure its not the subdivide sruface hiding them. its only on the arms some hair strands and the fingertips.
ok .....i have solved the problem , the problem was a bug.......i have uninstalled my blender 2.91 version ....and installed the 2.838 lts  version and this solved the problem .........lts version is better because they keep fix bugs