After you deleted the .wdtv folder did you then “Power Cycle” ie. Completely switch off the device then reboot ?
Also try clearing the media library as well (this will refresh the database)
Setup > System > Media Library > Clear Media Library
Do not do a Device Reset ! it is Not necessary …
as you are aware it will be a pain in the “you know what” :wink: to reconfigure the entire device again… just for a thumbnail change !
