Sitecore xdb rebuild index fails at finishing stage - sitecore

Question

we are using solr cloud with zookeeper for Sitecore 10.2 environment. We have created xdb and xdb_rebuild collections with aliases xdb_mainalias and xdb_rebuildalias respectively. When we trigger xdb rebuild, it moves all the way till finishing stage (95%) and fails there. When we dig the logs it says
[Error] An error occured during index rebuilding. There will be another attempt to check. The check interval after an error is 00:00:20.
Sitecore.Xdb.Collection.Search.Solr.Failures.SolrRebuildCoreNotFoundException: Collection name for alias: [xdb_rebuild] not found in Zookeeper configuration.
at Sitecore.Xdb.Collection.Search.Solr.SolrCloudRebuildHelper.<LoadCollectionNames>d__3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Sitecore.Xdb.Collection.Search.Solr.SolrCloudRebuildHelper.<SwapCores>d__1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Sitecore.Xdb.Collection.Search.Solr.SolrIndexRebuilder.<CompleteRebuild>d__10.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Sitecore.Xdb.Collection.Indexing.Rebuild.IndexRebuildFlow.<CompleteRebuild>d__28.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Sitecore.Xdb.Collection.Indexing.Rebuild.IndexRebuildFlow.<RunRebuild>d__25.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Sitecore.Xdb.Collection.Indexing.Rebuild.IndexRebuildFlow.RebuildStatusWatcher.<>c__DisplayClass5_0.<<Start>g__RunRebuildFlowCycle|0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at Sitecore.Xdb.Collection.Indexing.Rebuild.TaskExtension.<ExecuteWithInterval>d__0.MoveNext()
We have already uploaded configs to zookeeper and created xdb collections using the same. Are move missing anything here?