KQL error 'project' operator: Failed to resolve scalar expression named 'state'.

I am trying to create a simple use case based on the Signin logs for the "detection of singin from a single username from two different location".

Please find below the query:-

SigninLogs
| where TimeGenerated >= ago(24h) | evaluate bag_unpack(LocationDetails) | project Identity, state| summarize dcount(state) by Identity | where dcount_state >1

I am getting the error

'project' operator: Failed to resolve scalar expression named 'state'.

I tried to extract the locationDetails through extend command also but same results.

Please let me know the following:-

1) Are there any limits on the operations/usage on the dynamically extracted fields in Sentinel?

2) What limitaitons are there?

3) Please suggest a solution so that I can use the State field to get the required results.