Thanks for using Cloudera Community. Based on the Post, Your team is deleted data from a HBase MoB Table & experiencing no HDFS Size reduction post Compaction as well.
Wish to confirm whether your Team is checking the Size of the Table within the Table Level Directory (/hbase/data/<NameSpace>/<Table>) after the MajorCompaction. Additionally, Check the HBase Data Directory recursively for the concerned Table Name (hdfs dfs -ls -R /hbase | grep <TableName>) to confirm if the concerned Table data is being persisted within the Archive Directory. If the Table Data is being moved to Archive Directory, Check the HBase Master Logs for Cleanup details post TTL. Else, enable HBase Master Trace Logging to fetch granular details on the Cleanup activities pertaining to the Archive Directory.