**System Information**
Operating system: Manjaro Linux
Graphics card: AMD Radeon RX 570 8GB
**Blender Version**
Broken: 2.92.0 Alpha - October 24, 23:23:18 - 05129bc821fd
Worked: 2.90.1 (current stable version on Steam)
**Short description of error**
Until recently you could take any number of objects into edit mode, go to the material tab, select a material, hit the select button and it would select all the faces through all the objects that have that material assigned to them. But as of some recent change, the button will only work on the active object, ignoring all the other objects, even if they share the same material.
This is very important behavior for a tile based game porting project I'm working on that is getting multiple small texture atlases combined into larger per stage atlases, as I often need to select all tiles and select all faces with a given material so that I can resize and reposition their UVs for the new larger atlas all in one go. What used to take 15-20 minutes for a whole stage, would now take hours if I have to do that for every material on every object one by one (usually 100+ tiles with 1-8 materials each). For now I can keep an older build on hand, but I'd obviously really like to see this behavior eventually restored.
**Exact steps for others to reproduce the error**
Start with the default scene, give the cube a material, duplicate the cube, put them both in edit mode, deselect all, then try the select button on the material panel. In current stable, it will select all the faces in both cubes that are using that material. In the latest alpha (and I think most for the past few weeks at least) it will only select the faces in the active object.