Why are we seeing "Missing Def: Fieldplaceholder" in workspaces instead of a custom field?
Custom Fields, Workspaces, All versions
Edit the workspace where the behavior is occurring, remove the custom field that is not displayed properly and re-add it.
This behavior appears when a workspace containing a custom field is exported and imported into a site where that custom field does not exist. Even if the custom field is added later, it will not be automatically associated with the workspace. This is why it must be manually removed and re-added on the workspace.
If a custom field is deleted and then recreated with the same details (name, data type, column name), it will be re-associated automatically with all the workspaces where it appears, but this only happens on the same site. If the workspace is imported in another site and the custom field doesn't exist on that site at the import time, the field will not be available on the workspace unless it's manually re-added to it.