Heated print bed cutting off

Does anyone know what could be causing my heated print bed to cut off randomly? I have a Tenlog TL-D3 Pro and slice with Cura.I don't think I have changed anything about how I print or slice. It has been going on for a few weeks.I can not find a pattern - the programmed temperature just goes to 0 and the heat cuts off.I have tried to watch to see if the bed is overheating, but I haven't seen any indication of that.I have not yet seen the moment when it cuts off, tho.It's very frustrating to get half way thru a print, just to have the heat cut off and lose bed adhesion.Any ideas about what I can try?ThanksDonna