I haven't done Park of Easter Joy yet. But I did get Path Not Found for Easter York Under Attack, and Old Easter Factory yesterday while playing from the web portal. LTF never once created its golden trail from anywhere in either of those locations. Just Path Not Found over and over again.
The next day I eventually found the one missing tile (a chicken hat) in York Under Attack by looking for it by myself. For Old Easter Factory, I opened that location up in my phone, and LTF worked perfectly there and found the egg cup I had missed.
That chicken hat is bright yellow, yet I'm missing them pretty consistently when they are in a corner. I don't seem to see the egg cups either, especially if they are near any other egg decorations.
Seems to help just to forget about it for a couple of days, and then come back and look later.