Plugins' privacy usage variables are not being transferred to plist

When building an ionic project with ionic cordova build ios --device --release the usage description values for the following plugins are not generated in the resulting plist. This was verified to work correctly in the same environment in previous versions of cordova (6.x).

{{<plugin name="cordova-plugin-camera" spec="^2.4.1">
<variable name="CAMERA_USAGE_DESCRIPTION" value="Rallyest would like to access your camera to capture photos and videos" />
<variable name="PHOTOLIBRARY_USAGE_DESCRIPTION" value="Rallyest would like to access photos and videos in your photo library" />
</plugin>
...
<plugin name="cordova-plugin-media-capture" spec="^2.0.0">
<variable name="CAMERA_USAGE_DESCRIPTION" value="Rallyest would like to access your camera to capture photos and videos" />
<variable name="PHOTOLIBRARY_USAGE_DESCRIPTION" value="Rallyest would like to access photos and videos in your photo library" />
<variable name="MICROPHONE_USAGE_DESCRIPTION" value="Rallyest would like to access your microphone to capture movie audio" />
</plugin>}}

As a workaround, these can be set explicitly via:
{{<edit-config file="*-Info.plist" mode="merge" target="NSCameraUsageDescription">
<string>Rallyest would like to access your camera to capture photos and videos</string>
</edit-config>
<edit-config file="*-Info.plist" mode="merge" target="NSPhotoLibraryUsageDescription">
<string>Rallyest would like to access photos and videos in your photo library</string>
</edit-config>}}