Hi
This is indicative of a communication problem between MFP and Betfair API. Most commonly this is an unstable internet connection, e.g. wifi or broadband dropping out, or sometimes Betfair API momentarily down. MFP should automatically re-establish a link with the API as soon as it can.
Before restarting MFP please check the program log for any red error lines which could give an indication of the problem. If this happens frequently then I would say it is likely to be your internet connection. Also the number of markets concurrently refreshing and their respective refresh rates will have a bearing on the data request queue. Check this setting in Monitoring Options:
Limit the number of simultaneously refreshed markets/events
Save your traffic and computer resources by using this setting to limit the number of markets or events you want to refresh at any given time. The program will block the refresh of any market/event beyond the set number and put it into a waiting queue, even if it is time for that market/event to be refreshed according to the relevant monitoring options. Once you or the program stops or deletes some market/event, those put in the queue will start refreshing automatically. The priority is given to the market/event with the closest starting time. If the market is put in the waiting queue, you will see the hourglass icon on its start/stop button: