Hello,
I was about to post about this exact issue. The tenor shots (as well as rims) are being shown in the notation, but the playback is silent.
I followed this whole thread and tried the various things you suggested, but the solution for you (the 2.5 library re-installation) didn't work for me. So, I'm now lost.
I'm operating on OSx 10.9.4, have Sibelius 7.5, and VDL 2.5.5. 
Any suggestions would help.
-Andrew