QGIS » QGIS Application

It is by no means happening all the time.... just occasionally!
I am also having other issues where running an intersect process between to overlapping layers is dropping out some features on a random basis - and I can't seem to identify why - perhaps it is somehow all related??

This is the only one I have noticed it with.... but then I'm not uploading all my layers into another platform such as AGOL to view!
It looks fine in when viewed in QGIS - it is only when it is opened elsewhere that the anomaly presents.

I ran "check geometry validity" and there was 1 duplicate node in an unrelated polygon. I deleted it and re-uploaded and the 'old' feature shapes are still visible in AGOL, so it has not resolved the problem.

I would not consider overlapping features to necessarily be a topological error! They could be, depending on what they are representing, but there are many reasons by a shapefile (or any GIS layer) may have overlapping features or gaps.

I say it is a regression. I will check with dev, 2.10 and 2.8.

Could you also check with QGIS processing toolbox. For example my original bug, if I remove a feature and buffer it using SAGA, it will create a buffer of the deleted feature.

This affects the feature count. Deleted features still appear in feature count.

There are definitely two 'phantom' objects that remain in the table unless a save-as is done.
Simply by populating a column with $id, I can see that the count gets out of sync at the last two features.

I tried the SAGA Buffer in Processing Toolbox, however this actually results in only the first 13 features being buffered. I also tried a "Convert polygon/line vertices to points" and only the first 13 records have vertices created. I believe it may be stumbling across an issue with the 14th object and it simply stopping going any further, as I created a new feature in QGIS (a simple polygon with 4 vertices) and re-ran the buffer and vertices>points process and both results still stopped at the 13 feature...

However, even after deleting the 14th and all subsequent objects except the last one just added as a test object, it still fails to buffer the new test object.
But if I save-as the shapefile and buffer it, it works perfectly and buffers all features.

(All this testing has been done on the same shapefile uploaded in my previous update.)

If is provides any additional context information, many of the objects in our GIS layers are being extracted from DXF CAD files - thye appear to import through into the GIS format and copy/paste perfectly fine, but perhaps there is some underlying object issue that is somehow causing issues? We have recently had other objects that 'dissapear' when an intersect process is done - however all objects pass all the geometry validity checks...