Issue was reported in https://h5p.org/node/113857
Steps to recreate the issue:
1. Create a Single Choice set (Stand alone or embeded in Column, Question Set and Course Presentation)
2. Uncheck "Enable Sound Effects"
3. Answer some questions wrong
4. Click on Show Solution button - Nothing happens.
Below are 2 test contents:
Embeded in CP
Stand Alone
Contents created in H5P.org
Tested in:
OS: macOS Sierra (V10.12.3)
Browsers:
Firefox Version 54.0.1 (64-bit)
Chrome Version 60.0.3112.101 (Official Build) (64-bit)
Safari Version 10.0.3 (12602.4.8)
Disabling the sound effects should not affect the show solution option.