I have just tested this in a lab environment and I am able to reproduce using both the MA 5.0.4 and 5.0.3 Extensions in ePO 5.3.2.
As a result it would suggest a problem with the ePO 5.3.2 build - I will apply the latest hotfix to the ePO server and see if that resolves the issue.
If it does not I will raise a support case as well.
Thank you for the sanity check. As it turns out from our testing the delay value does get saved, but it always displays zero. I haven't heard anything from our SR yet, but I assume this is a bug in the agent management extension as well.