Why is replication stopped?
Has anything been written to the Master in the last 72K seconds (about a day)?

Sometimes this helps:

STOP SLAVE;
START SLAVE;


I have seen the need for this on and off over the last decade; never figured out why it might be needed.

Another mystery is that the Seconds_behind_master sometimes mysteriously decides to flap between zero and some large value.  Eventually that problem clears itself up.