I can really sympathise as to how annoying it is. Milo has been doing this for sometime and is getting worse. If he wants to go in a certain direction and I want to go the other way he either lays there or stands there planted into the ground. If he sees another dog he wants to say hello to he will refuse to walk in my direction. Same if there is something he wants to stop and sniff.
He knows I can't just drag him because he will duck his head and his harness comes off and he is gone, with no intention of being caught. Luckily being small I can pick him up and walk off with him and that worked for a while but now when I put him down again he will root to the spot again.
I can get him to move for a treat but then as soon as he has eaten it, he stops dead again and won't move till I offer him another.
Grrrrr they really do try your patience at times.

Ollie does the same when given a treat, unfortunately I can't pick Ollie up, I sometimes wonder why I didn't get a smaller dog I could then pop it in my pocket when it did these things.
Nice to know I am not the only one suffering. He had got a lot better, so I am hoping it is a blip and not going to become a habit again

Had abit of A GIGGLE I'm afraid, hope you calmer now xxx

Yes thankyou didn't take me long to get over it and have a giggle myself, not sure what the woman with two spaniels thought when she saw me stomping off and leaving him on his own.
He was a good boy this morning, fingers crossed it continues.

I have a lot of these 'just when everything was going so well...' moments too. They can be devils at times these boys!