Hi Venkat,
1) Ensure whether valid prompts are applied or not.Because when we give wrong propmts, report get stuck & takes long time ending with NO result.
2)Check main KPIs dimension objects are fetching data or not in separate report. This is to ensure that internal KPI dimensions objects formula are not changed mistakenly.
3)If report is taking 30 mins in prod, Please check same report in QA and DEV. If QA/Dev works in 1-2 mins, then check & compare query filters/result objects of PROD with QA/DEV.
4)Check Array fectch parameter at universe and check size for row/column retrival is changed mistakely.
5)Try executing the query in database, to check whether query is taking long time in database as well or not. If its not taking long time in DB then some issue is in report itself
Let me know if this above approaches works for you.
Br,
Bansi