Comments and chat messages disappear after app inactivity

My app’s URL:

My app contains comments and few chat messages. If I start the app, no problem, all comments and chat msgs are there. If I leave the app and keep it running in the background, then come back to the app after few minutes - difficult to estimates, I would say 10, ou 20min, the app is working as expected BUT the chat is empty and all comments have disappeared.

They should be persistent.