Workplane Grid Snap Extruded Poly Bug?

Here's a strange little issue I ran into while tooling around with workplanes today.  It may be down to user error, but it baffles me a bit if it is, so here goes.  If I draw a perfectly square polygon on the standard world grid using grid snaps, extrude that poly face into a box shape, and then bridge two edges on the back side of the "box" to close it... everything works fine - I've got a solid box (yes I could just create a box primitive instead, but that's not the point).  If I then turn on a workplane, lock that workplane in place, and repeat the exact same operation, but snap to the workplane grid rather than the world grid, I am left with a "box" that is left *open* on one edge.  If I box-select the open edge, the hud indicates that I have 2 edges selected.  If I then box-select one set of vertices attached to those 2 open edges... the hud indicates that I only have 1 vertex selected not 2?  I don't seem in any way to be able to collapse those "2 edges" together... and welding the verts doesn't work because there's apparently only 1 vert per corner.  It's as if there are 2 coincidental edges sharing the same 2 verts, which makes no sense at all to me.  I've tried this with various quad shapes, apart from squares, and always end up with the same result (one open edge left), provided that I use grid snaps on a workplane.

As another experiment, if I create another quad polygon  of any shape on the same workplane *without* using grid snaps (plane snaps are enabled instead), and repeat the same set of operations, I am left with a perfectly solid, closed mesh.

I've attached the first screenshot to highlight this.

I guess I should quickly add that using "Cap Hole" instead of "Bridge" closes the mesh up tight. HOWEVER, there's still a big problem with this method in that if I seal the mesh with "Cap Hole" and then try to "Inset" that created poly, it doesn't work properly, because there appears to be a problem at one of the verts, causing only 3 of the 4 edges to inset. 

I'm further testing it as I write the bug report and keep finding additional issues.  The problems actually seem to start at the very first polygon created  on a workplane using grid snaps... that original poly exhibits the same Inset error, in that only 3 of the 4 edges of the quad poly will inset.  If I try to box select the offending vertex/vertices, I find that I actually CAN'T select the vert/verts at all.  I can't weld it/them, and the HUD indicates that there's only one vert... but guess what I just found?  There actually ARE *3* verts, and I only discovered that because if I "Tweak" the vert, I can actually move it, and it it leaves the second AND third "hidden" verts in place... once I've moved 2 of the 3 verts, then yes, I can physically select and/or target-weld them, and finally end up with a clean 4-sided polygon.  A lot of effort to create a single grid-snap-based quad polygon on a workplane, eh?

I've attached a second screenshot to show the hidden verts issue.

Hi

It sounds like you are using "Create polygon" and not closing the polygon with the last mouse click (for a quad/square, the last(4 th) mouse-click should be on the first vertex created).

For selecting overlapping vertex, use RayCast selection= MMB+drag

Ok, for selecting the overlapping verts, RayCast selection does work (doh), which makes sense... probably should have tried that earlier, but didn't at the time because I either wasn't expecting stacked verts, or didn't know I'd have to raycast select for multiple verts occupying the same space.  Fine, we'll call that user error.

As for using "Create polygon" and not closing the polygon with the last step.... I certainly "thought" that is what I was doing.  Whatever shapes I created were done using 4 clicks, with the first and last click on the same grid point.  But I think I see now where the issue is, which is still a bit odd.  If I use "Create/Insert" to make a polygon in Vertex Mode, I click 1,2,3,4 times and the result is a quad with 4 verts as expected, every time... no issues.  If I use "Create Polygon" in Polygon Mode, I click 1,2,3,4 times and on the 4th click I MUST see the Icon that looks like a game controller directional pad before I let go of the mouse, or ELSE I get the issues described... like the polygon is not properly closed.  What I was doing before was just clicking 1,2,3,4 times and on the 4th time, I simply saw that the Snap indicator was lit up over the grid point from which I started creating the polygon and let go then... which made it look like a closed quad poly, but which exhibited the problems I described.  So, it appears that I can not rely upon grid snaps alone when using the "Create Polygon" tool... but I must ensure that the "close poly icon" or whatever it's called, is showing at the time of mouse click release.

Thanks for your help... I'm sure I won't run into the problem again now, but I'm still quite new to NVil, so it'll take a little while to learn the small quirks.

The tolerance of the close polygon is too small (about 4), it should either be increased to 8(default snapping tolerance) or be controlled by the snapping tolerance.

Hopefully IStonia will have a look at the problem when he has time.

It is improved.

It is improved.

There appears to be some improvement on the "Close" of the "Create Polygon", but only if closing is at a snap point on a pre-created mesh. If you using "Create Polygon" and not snapping to a pre-created mesh, still the same problem as before.
Also:-
Why does the "Create Polygon" tool completely ignore/not use "Snap to Grid"?