NMB vertex weld (clickless) works only with some vertices

(...) if mapped to NMB the program will pick up the highlighted vertex as first vertex on activation. Then move cursor over to the second vertex, click or release hotkey to weld.

This doesn't work 99% of the time. It appears to be weld only on some vertices.

What always works every time, is LMB-clicking on the first vertex and then releasing the hotkey when over the second vertex.
OR
LMB-clicking the first one and then LMB-clicking the second one.

To reproduce:
Create a sphere and split it in half. Move the upper part a little bit on Y+ axis and combine both objects.
Now, start welding vertices using the NMB method. None of them will weld.

Now, split the polar area of the sphere (that part that contains triangles). Move it up and combine with the rest of the sphere. You'll be able to weld all border vertices.

Can you show me in a video? I can't tell how you split the sphere and how you do the combine.

I made a few more tests and it looks like the problem occurs when I'm zoomed-out too much. Then the vertices won't weld with NMB Weld Vertices. But if I zoom-in close enough - they will.
Take a look: https://www.dropbox.com/s/sujq9t498m1y5vp/nmb_weld_vertices_affected_by_zoom.mp4?dl=1

If I use NMB Weld Vertices, but weld them by LMB-clicking, they will always weld, no matter how far zoomed-out I am.

I still can't produce the bug on my side. Can you send me your config files together with the scene file in the video?

Sent to info@digitalfossils.com.

Did you perhaps had time to look into the issue?
Maybe it's limited to 64-bit version of NVil?

Try this
http://www.digitalfossils.com/Download/NVil-Mar-29-15.rar

Hi rubberDuck,

Maybe it's limited to 64-bit version of NVil?

I have not seen that problem on my setup (win7 64)

IStonia, it looks like it's fixed in this version. Many thanks!