If there is a solid region which touches any pads or the middle of a track, easyeda does not merge the nets. The solid region will have a different net than the pads and tracks. There will be yellow Xs where they touch. Pads connected with a solid region will have a ratline as if they were not connected. This can be fixed by manually changing the net of the solid region to match the tracks and pads. But if you make some change which requires updating the net names, the net of the solid region will not be updated with the other nets, and will have to be fixed manually again. If a solid region touches the end of a track, easyeda merges the nets correctly. But only if the solid region touches the end of a track, not if the solid region touches the middle of a track.