Reimport factory not being called for import enabled by plugin

A user reported a problem that started occurring with 4.10 and didn't occur in 4.9.2 (Was unable to get a project in 4.9.2 and thus unable to confirm his claims, therefore I'm not marking this as a regression) where the reimport factory isn't called when source files are changed. This seems to only apply to the file type that he is using which is allowed to be imported by his plugin.

1. Download the attached project
2. Open the .uproject file
3. Locate the "objective_SuperLite" uasset in the Content Browser in the Content folder and double-click it to open its properties.
4. Navigate to the Simplified/Content/objectiveSuperLite/ folder in your File Explorer and open the objective SuperLite.epro file in Notepad ++ (Normal Notepad won't be able to load it correctly due to encoding)
5. On the first line, change the "sample rate" to any other number than what is currently listed and save the file
6. Notice that the editor mentions that it is "Processing source files..."
   Result: The Sample Rate for the asset never updates
   Expected: The Sample Rate should change to the value you changed it to