Dispatch folder is only 284KB but I still encounter minimum free disk space (5000MB) reached for /opt/splunk/var/run/splunk/dispatch

I wanted to reduce my storage space. I have already set retirement policy but my used space did not reduce although the error message is not gone. I did a ncdu on /opt/splunk/var/run/splunk/dispatch but the total disk usage is only 284KB. Am I looking at the right place? Can I delete all the files in Dispatch folder without breaking anything?