QGIS » QGIS Application

I've finally been able to reduce this features going missing issue that's been haunting me for a while now.

When doing multiple joins like this:

i.e. fields ORIGINAL -> joined fields A linked through a field in ORIGINAL -> joined fields B linked through a joined field in A

the values will get lost every now and then when those joins are cached.

Steps to reproduce

1. Open the attached join_cache test project
2. When the project opens, start rapidly panning the canvas around (small steps using the mouse's middle button is the easiest way)
3. You'll notice the dark pink polygons going missing after every few pans (see gonebabygone.mp4 video too)

This does not only affect feature rendering, saving the layer (with all its joins) can actually write null values for joined fields B.