Unable To Unsolo or Solo Sound Waves

Sound Waves are not able to be soloed in a new project or unsoloed in an existing one from a prior version.

This was reported and tested in 4.24.3 (CL-11590370). This was reproduced in 4.25 (CL-13144385) and Main 4.26 (CL-13544465)

1. Open the UE4 Editor and create a First Person project
2. Navigate to FirstPerson>Audio and right click on FirstPersonTemplateWeapon then click the checkbox for Solo

Results: You can't set the sound wave to Solo. If upgraded from a prior version you can't unsolo a soloed sound wave

Expected: To be able to solo/unsolo a sound wave