About missing vitalsigns in the MIMIC-IV ED

Description
Thanks very much for MIMIC IV database, which provides a very good learning platform for medical researchers.
Here I would like to inquire about the problems encountered in the process of data extraction, looking forward to your reply, thank you very much.
My research content is mainly limited to the ED module, so the vital signs of the target population are crucial to my research. However, in the process of data extraction, I found that some patients were missing vital signs, and they stayed in the emergency room for more than 4 hours, but there was still no record of vital signs. I don't quite understand why this happens, is there any other way I can get this part of information?
I tried to extract the vital signs information from the triage table, and I tried to find them in the vitalsign table if they were not recorded in the triage table. In the vitalsign table, these patients did not even record the chartttime.
I need this part of data very much. If you have other extraction methods, please help me. Looking forward to your reply, I would appreciate it very much

Start by reviewing the reported extraction path through the triage and vitalsign tables, focusing on patients with more than four hours in the ED and no charttime. No repository file or test is identified in the issue. Done means documenting whether these records are expected to be absent and identifying an available extraction method, if one exists.