A recent Microsoft Windows 10 update may have disabled/turned off the SMB1/CIF option. WD has a knowledgebase article discussing how to turn the feature back on:
It should be noted that the reason Microsoft disabled this feature is due to security vulnerabilities. See the following Microsoft blog post. So reactivate SMB1/CIF at your own risk. One can still access and map the My Cloud using the device’s IP address or possibly the device name.
