I’ve figured it out. Hopefully, anyone else running into this problem will benefit from this thread.
Shafayet, regarding your comment about backing up before updating, I back up daily, if not more often. As I stated, I was able to restore the deleted file from my backup.
Doc Dunning, I appreciate you chiming in. However, my custom templates have unique names and those unique names are used within the template file, as well.
Shariar, your response got me on the right track. However, it was WP Download Manager “documentation” that got me in this mess in the first place.
For your reference.
https://www.wpdownloadmanager.com/doc/short-codes/
According to this documentation, you are to use the “Template ID” in your short-code to source the template you desire. This does in fact work IF your custom template is in the “\wp-content\plugins\download-manager\tpls\link-templates” folder. However, once you move your custom templates to the “\wp-content\themes\my-theme\download-manager\link-templates” folder they will no longer work if you use the Template ID alone. You must then add “.php” to the end of the Tamplate ID in your short-code or your custom template WILL show up in Downloads > Templates > Link Templates (tab), but will NOT be sourced when you view the page, widget, etc. you’re using the short-code on.
Just a wild guess here…
Maybe there is a difference in the plug-in code between the free and the pro version of WP Download Manager?