Problems with Lovelace Configuration Files in /config Subdirectories

I have a Lovelace dashboard in which some of the controls are included in configuration.yaml using !include_dir_merge_list, for example:

input_number: !include_dir_merge_list input_numbers/

The directory input_numbers is a subdirectory of config/ and the template file is minotairInputNumbers.yaml.

If I do that, the Lovelace dashboard controls are greyed out. But if I include the file directly in config/, the controls are active.

The control for the switch: key is also located in a subdirectory and defined but it is active, as are the sensor: displays and automations:.

Why should Lovelace have a problem with certain controls being in subdirectories but not others?

Any suggestions?