Armature not affecting both sides equally

Rigged up my dragon on one side, duplicate and flip. The FLIPPED side works great. The ORIGINAL left side has a problem with the rig affecting the foot. I have to go in and weight paint the whole foot red as shown in the picture. But it doesn’t work like the right side, which moves the whole foot along with the bones as expected. I’ve re-rigged it, started rig from scratch several times. The issue is there before I duplicate and flip, but it doesn’t effect the flipped side.Both legs in picture are flexed from rest pose. Only the right one deforms correctly.
Blender File is here:


In weight paint mode, Tools panel, check ‘Auto Normalize’, then brush over the section with the ‘LegLowerL’ selected.
The geometry should now pop back to its correct position…

THANK YOU MOTIMO! Now I can get on with the rest of this project. I look forward to finding out WHY that needed to be done.
Thanks again!