Created attachment 1212744 [details]
screenshot-syncplan.png

Version-Release number of selected component (if applicable):

Sat 6.3 snap 5
foreman-1.13.0-1.el7.noarch
katello-3.2.0-2.rc2.el7.noarch

Steps to Reproduce:
1. In UI (content > sync plans > new sync plan)
2. Create a hourly sync plan with start date sometime in future, save
3. View the new sync plan, edit the Interval field, select weekly from the drop-down list. Click save.
4. The Start Date field turns to "Invalid Date" and an error is displayed -- see screenshot attached. Next Sync field is not adjusted, unable to save.

Expected results:

Valid start date is unaffected after changing the sync plan interval, next sync is properly adjusted and the sync plan can be successfully saved with changed values.

Additional info:

Excrept from /var/log/foreman/production.log attached.