What you mean with Thumbnails? Previews the finder shows? CS4 is not 100% compatible with OS 10.10. Illustrator and Photoshop might not work properly. Thats why my agency had to upgrade to CC.
You're lucky you can get CS4 to run under Yosemite at all. There are no guarantees at all of compatibility.
Yes. The thumbnail previews in Finder look like blank documents. Not a big deal. Just annoying. All other CS4 program thumbnail previews show up as before. Just not InDesign.