Hi,
Please go to SE38 and try to execute the report SAP_INFOCUBE_INDEXES_REPAIR
It will drop all the indexes and recreate it.
Recently we faced few index related issues like slow performance due to corrupted indexes.
We executed this report which drops all the indexes and will be recreated it correctly.
Based on the DB size, the report will run for some time.
Keep your database stats up to date and try to run the above report.
I hope it helps.
Thanks and Regards,
Vimal