please check the table WMERROR if the required fields are long enough.
Depending on wM Version your are on you might need to update IntegrationServer/audit/schema definition files to adopt the change in lenght. Restarting IntegrationServer is required afterwards.
MWS itself does not hold the data but uses IS (WmMonitor) to access the data.
please check if you have the latest updates for your ISCoreAudit component applied to the database.
On the other hand you can modify the length of the column at your own risk to 4000 chars.
Restart the IntegrationServer for AuditLogging to notice the changed length.