I'm new to QGIS, but I'm experiencing what I think is a bug.
When I load the qgis_sample_data landcover raster and lakes vector layers, then enable labels for NAMES on that layer, I can only ever view one label at a time.
I've disabled simplified geometry and enabled "show all labels for this layer (including colliding labels) still to no avail.
I've attached an imgur album of screenshots to demonstrate the problem - the only thing I'm changing in those screenshots is the zoom level or pan.
Using QGIS 2.8.3 for Mac OS X Yosemite.