Concurrent/Schedule index creation is failing with "GSI index id 1a235de568fd78c3 not found"

I'm creating close to large no.s (~1000) of concurrent indexes. Basically I'm running 10 index creation query in parallel every 5 seconds till index count reaches 1000. In some iterations query fails with following error - 

AssertionError: CBQError: host 10.112.190.101: ERROR:{'requestID': '3441defb-d8c6-4c40-92fe-77d90ec3bb8e', 'signature': None, 'results': [], 'errors': [{'code': 12016, 'msg': 'Index Not Found - cause: GSI index id 1a235de568fd78c3 not found.', 'retry': True}], 'status': 'errors', 'metrics': {'elapsedTime': '263.496234ms', 'executionTime': '68.923464ms', 'resultCount': 0, 'resultSize': 0, 'serviceLoad': 75, 'errorCount': 1}}

I've attached cbcollect_info logs.

Steps to reproduce.

1. create 1 node cluster with KV-n1ql-query service and 1B-1S-1C
2. load some 10k docs
3. Create 10 indexes in parallel with 5 sec pause between each iteration till total no. of indexes are equal to 1000.