I am sharing workaround from my observations.
Login to setu and try to complete as fast as you can like within 60-90 seconds.
Don't inititate next txn without log out and logging in again and doing txn quickly. Keep clearing browser date or use incognito mode and then close browser and open again. On mObile phone keep clearing you data in privacy. I always use my laptop (except in case of jioFin which is dead now).
If you move away from setu page to another page/tab, it can lead to problem so stay there to avoid session expiry problem.
Setu thoda possessive nature ka hai from last month. Idhar udhar jayo toh fail kar deta hai txn.