How to reproduce:

1. Create two new folders (TEST1 and TEST2 for example)
2. Add files to the folders
3. Remove "images" folder if it exists.
4. Collapse TEST2 folder and expand TEST1 folder. The Assets Library should look like this:

 5. Rename the "TEST1" folder to "TEST3" folder. After this it should logically look like this:

But it looks like this:

It seems that after renaming the folder the alphabetical and numerical order of the folders/files in the Assets Library seems to mess up which folder is collapsed and which one is expanded.