`_lastUpdated` is listed as a SHALL search parameter for multiple profiles. Though {Resource}.meta.lastUpdate is mandatory but {Resource}.meta is not. That means if a server does not support {Resource}.meta, all resources from the search are still valid but server could not do `_lastUpdated` search since no instances has that element.

Suggestion:

either

• Mark {Resource}.meta as mandatory, or
• Change _lastUpdated as SHOULD support.