The AM/PM value is not shown in the cell when formatting a time value.

Steps to reproduce:
1. Insert some time in a cell in spreadsheet (22:20)
2. Apply it a custom format that contains AM/PM (e.g. "h:mm AM/PM")

Observed: The AM/PM format is missing
Expected: AM or PM should be shown after the time (image attached) 

Declined: The changes could be applied if the user presses OK button instead of pressing Enter key. A new feedback item is open where the issue is described: https://feedback.telerik.com/Project/143/Feedback/Details/212042-spreadsheet-custom-number-type-values-in-format-cells-dialog-are-not-applied-wh