labelingqgis
The 3.10 changelog mentions that label callouts are now available. However I have not been able to get them to display, no matter what values and options I enter in the Layer Styling > Callouts window. That is, no lines extend from labels to features. Instead, I get the previous version labels, which are centered over the features.
I also tried with 3.12; no joy.
What am I missing?
One more thing that took me a while to figure out is to make sure there aren't any graphics blocking your labels. Do this by going into your Data Frame Properties and the Annotation Groups tab to turn off all annotation groups. If your labels appear now, it's because a graphic was blocking the rendering of the feature label. Converting the labels to Annotation is the only way I've found to make the labels appear over top of graphics.
It seems the graphics engine in ArcGIS isn't smart enough to determine that a diagonal line only takes up a one dimensional space. Instead ArcGIS draws a rectangle big enough to encompass the diagonal line, causing any feature labelling that is overlapped by this big rectangle to not display - even when the line itself isn't overlapping the labels.
However, this artcile explains how to fix the issue. For ArcGis 10 see the label weight ranking tool
You don't need data in the attribute table to apply a label. You can apply an identical text label to every feature in a layer by simply entering text surrounded by single quotation marks.
If you want each feature to have a unique label, that's where you would need information in the attribute table. Add a field to the attribute table, give each feature a value in that field, then use that field in the Layer properties > Labels > Label with... Here's a quick photo guide to adding a field to the attribute table:
These are pretty basic tasks in QGIS. If you take the time to work through these QGIS tutorials, you'll have a much easier time using this program.
Best Answer
After ensuring the 'Draw callouts' checkbox in the Callouts tab, set the 'placement' setting to 'cartographic' and 1-2mm from symbol bounds.
You won't see a callout unless the label is a distance from the symbol.
This will be a way to test the callouts are working by moving all the labels en masse away from the symbols.