Was the 'Noise Reduction Pack' (formally known as NR-2.0) check-marked on the installation manager when you initially installed SFP-15. In any case you can reinstall it . Run the install manager and only check-mark the NR Pack. The install manager may still be in your "Documents> MAGIX downloads" or in your 'Downloads' folder. (soundforgepro15_dlm_ku3zs9.exe) You can also add the NR Pack tools (Noise Reduction; Click and Crackle removal; Clipped Peak Restore) in the FX Favorites (Organize> Direct X, and drag the desired NR tools to the Favorites folder or sub-folder) FYI, RX Elements basically has the same tools as the NR pack, but are more refined.
Also confirm Pro-15 is Build 45 (SF Help menu> About SF). If it is not, download from the "Magix Service Center> My Products" and re-install Pro 15 as well.