Dynamics 365 is accessed via the OData v4 REST API, which requires a single XML file containing all metadata for an instance to be retrieved prior to any other actions. Dynamics 365 incorporates a lot of objects which makes this metadata file quite large in most cases, so S4D caches a copy locally.
Because of this caching mechanism, S4D will not recognize schema changes in your Dynamics 365 instance immediately and it will be necessary to remove the cached copy.
TODO: Status page metadata removal/reload
Metadata files are automatically downloaded and cached in the directory defined in the \App_Config\Modules\S4D\S4D.config file:
<sitecore>
<settings>
<!-- The location where Metadata files for Dynamics connections can be stored, must have write access. -->
<setting name="FuseIT.S4D.MetadataDirectory" value="/App_Config/Modules/S4D" />
</settings>
</sitecore>
Files are named based on the Dynamics 365 domain. It is generally safe to delete any files not in use, a fresh copy will be automatically downloaded when next required.
If the web server process does not have write access to this location then the metadata file will need to be download for every Dynamics API request, which may have a performance impact.