Problem with Lines/Surface

Hello, I have a problem with surfaces and lines. I have this flat surface, I drew lines forming a closed surface on it, and 1) it only wants to do a closed surfaced in some places and 2) as on the attached video, the lines flicker on and off, and disapear as I zoom in, as if they were just under the surface but not on it.
Yet I know that the surface is flat, and that the lines are stuck on the surface…
Am I doing anything wrong or is this a bug ?
Thank-you !

Share the .skp file so we can see exactly what’s going on. I expect there’s a solution.

It’s a bit heavy, shall I try and separate the important part into another file ?
My computer’s slow, so it’ll take a while.

No. Upload it to Drop Box or Google Drive and share the link.

Can’t access to either Drop Box or Google Drive, computer restrictions.
Is it ok if I share the file directly here ?

Prob lines.skp (4.7 MB)
I’ll have to go though, I’ll be back latter.

I expect the problem has to do with some small overruns or gaps. You have Length Snapping enabled and that can make it more likely to get those sorts of problems. Instead of chasing around looking for them it was simpler and faster to redraw the lines. It would be easier to do the modeling if you wait to add the materials until after you have the geometry in.
Prob lines fixed.skp (4.6 MB)

You should correct the reversed faces. No blue back faces up.

Thank-you, I appreciate the help and time you took.
But I still have the problem of not having a closed surface…


Any suggestions ?

After all it’s ok, I managed to fiddle a way out!