Steps to reproduce:
1. Open any Unity project
2. Make sure the Layout of the Project panel is set to Two Column (icon in the top right corner of the panel->Two Column Layout)
3. Add any folder to Favorites (drag and drop)
4. Select a folder that is not under Favorites
5. Adjust the bottom right slider in either direction
6. Click on any of the folders under Favorites

Expected result: icon size does not reset
Actual result: icon size gets reset (see attached video)

Reproduced with: 5.6.0f1, 2017.2.0f3, 2018.1.0b4, 2018.2.0a5