Hi @Candice Guo ,
Thanks for your patience. Reason for the above discrepancy is as ADF code is evaluating rand expression twice - when pipeline is actually running and when wait time is reported as input. Since the expression is rand function it results in different values. Product team confirmed it as a bug and work item is created for fixing it.
I will coordinate with the internal team to get this fixed and I will update you as soon as I have any updates.