After the creation of a reusable Sender/Recipient pattern, Enforce shows event 1202 "No policies loaded" or 1201 "Loaded 0 policies". No policies are actually loaded on detection servers.
Event 1202 "No policies loaded" or 1201 "Loaded 0 policies"
This is a known issue, which was fixed in a subsequent release of DLP.
The workaround is to restart the MonitorController service on Enforce to reload all policies.
As per the Release Notes, this issue was fixed in 12.5.2:
3634770 "Policies were unloaded after editing sender/recipient patterns."
Note - this fix is also present in the latest release update for this branch, 12.5.3, which has the most recent fixes and is recommended.
See release notes in the linked KB for more details.