It seems like lots of people are finding the Rotate feature in both the Browser and the Bridge to be, well, let's just say unreliable. Here's a workaround I use. Rather than using the Rotate button, try creating some Actions, one that roates images clockwise and another that rotates them counter clockwise.
In the Bridge, or Browser, select the files you want to rotate, then
Choose Tools > Photoshop > Batch
The Batch dialog box appears.
Select the appropriate Rotate Action and run it.
The files are rotated.