Hi Stevland,
When using the demo site (1.18.1-1) provided on osticketAwesome.com, the Schedule Entry with option set to “Repeats: Once” can be created but when updated the “Starts On :”, it cannot be saved and the pop up screen below keeps shown up on windows screen.
It was the same situation which happens on my on-premises production and UAT sites, would you please help check, thank you very much.