Application Manager - Last sync with store showing invalid date for 'dd-MM-yyyy' date formats

The 'Last sync with store' date and time is displayed incorrectly or as invalid value, when 'glide.sys.date_format' has been set to certain formats.

Date formats supported by Application Manager before Washington DC Patch 5 are 'yyyy-MM-dd' and 'MM-dd-yyyy'.
On instances where date format is different, for example 'dd/MM/yyyy', the date displayed will be wrong (day is month and month is day) or an invalid value is shown.

However, even though the date displayed is wrong or invalid, the sync still happens and there is no functional impact. This is only a display issue.
To confirm, you can see the true last sync value in 'sn_appclient.apps_last_sync_time' property (in sys_properties).
The value here will be in 'yyyy-MM-dd HH:mm:ss' format, always, regardless of what 'glide.sys.date_format' is set to, and will be displaying time in UTC/GMT timezone.

1. On an instance with default glide.sys.date_format, in the filter navigator, go to 'System Applications' -> 'All Available Applications' -> 'All'.  This should open the Application Manager.
2. Click the 'Sync apps' (double arrow circle) button next to the 'Last sync with store' date and time. Wait for the sync to finish.
3. The date will be displayed correctly.
4. Set glide.sys.date_format to 'dd/MM/yyyy'.
5. Open the Application Manager again.
6. Observe that the 'Last sync with store' date is incorrect (day is month and month is day), or invalid.

The issue is fixed in Washington DC Patch 5 and higher.
Application Manager on these releases will support the following formats:

• yyyy-MM-dd
• MM-dd-yyyy
• dd/MM/yyyy
• dd-MM-yyyy
• dd.MM.yyyy

On impacted releases, there is no workaround other than setting glide.sys.date_format to one of the supported values: 'yyyy-MM-dd' and 'MM-dd-yyyy'.