Solution : https://service.sap.com/sap/support/notes/1564210 (SAP Service marketplace login required)
Key words : 
inactive bwa indexes typically lead, serveral bw accelerator indexes, index manual activation/deactivation, sets inactive bia index, request deletion process terminates, inactive bwa indexes, bwa index usage, bi accelerator index, bia remains inactive, bia index 'inactive'
Related Notes : 
       
| 1559754 | Enhancement RSDDTREX_ALL_INDEX_REBUILD | 
| 1512663 | Request deleted by sets inactive BIA index to active | 
| 1495735 | check of changed records between DB and BIA after changerun | 
| 1385320 | Error Handling in Consistency Check for DB Vs BIA - Updated | 
| 1371487 | BIA: Several problems related to BIA and change run | 
| 1320492 | Deletion of hanging requests in BIA | 
| 1317485 | Error Handling in Consistency Check for DB Vs BIA | 
| 1298405 | BIA - Request deleted from BIA only | 
| 1172236 | Metadata adjustment terminates in the BIA | 
| 1162641 | BIA: Incorrect data after compression terminates | 
| 1159260 | Counter for BIA read accesses | 
| 1149531 | BIA index status "inactive" | 
| 1125042 | BIA remains inactive after a request is deleted | 
| 1108784 | Request deletion process terminates, status of the BIA index | 
| 1076838 | BIA index 'inactive' after parallel roll up & change run | 
| 1070848 | Several problems with BIA indices | 
| 1012008 | BI accelerator index after activating the InfoCube | 
| 987696 | BIA index not set back to 'active' after you delete request |