To reproduce:
1. Import an audio clip
2. Set it's load type to DynamicLoading
3. Add it to scene and enter play mode - no sound plays

Explanation:
This is not a bug. When you set a sound to be dynamically loaded, you need a script to call AudioClip.DynamicLoad on it first to actually do the dynamic loading before you can play it. The idea is that scenes can reference all the sounds they need, but the memory footprint of these is very minimal until the sound is actually used and the script requests it to be loaded. Note that the arguments of DynamicLoad provide various ways how to load the sound.