Hello,
I think you are mixing 2 concepts:
1) DLP services edpa.exe and wdp.exe stopped
2) Agents with Critical / Warning status
Answering your last line, the agents will be on critial/warning groups (agent alerts) if the machines are not reporting or they have some issue.
To know more about the agents alerts check this link: https://support.symantec.com/en_US/article.TECH186331.html
Bear in mind that it's possible to set on "System / settings / general" when an agent will switch from Reporting (OK status) to Not reporting (Critial status) based on agent last connection.
If the DLP services (edpa/wdp) are stopped on your machines that's probbaly because of a corrupt installation. In such situation the agent do not report and fall under Critical status on Agents List.
BR,