Steps to repro:

1. Create new project;
2. Import attached 'treePackage unity package';

3. Notice that errors 'SpeedTree materials need to be regenerated.' are displayed in the console;
4. Click on any SpeedTree material error listed above;

Expected result:
.spm model, which material should be regenerated, is highlighted in 'Project' folder.

Actual result:
There is no reference to selected SpeedTree model (see attached gif video).

Notes:
- Reproducible in 5.6.0b5; could not test for regression, since for previous versions .spm models are up-to-date;
- Reproducible on both Windows 10 and OSX 10.12.2.