"No filiment"...

Have a 5 and used it a bit No problem. However suddenly getting message that there's no filament and it's asking to load or unload. I have loaded and unloaded and when loading I just get a pile of strings until Ai end the load but it still reports no diligent when I restart the print.

Do I need to replace the filament detector? If so why would it die so quickly when I have used about 1/3 of a spool so far with the machine?