After upgrading from 15.8.0 to 15.9.1, the FTE values show in seconds. This is in the Modern UX: Staff module under a Project.
Refer to the screenshots below;
For example: After allocating a resource for one day in a project, instead of seeing 1, I can see the allocation of 28800.
In Classic it shows OK.
This was working fine before the upgrade was from version 15.8.0.
Release : 15.9.1
Component : Modern UX - Project
This issue got resolved after flushing application caches (FLUSH ALL from the security.caches page) re-slice of allocation slices. The Time Slice job had not yet been run.