Can't Edit Marker

I have added 4 markers to my map. When I add a 5th marker, it shows up on the map, but it doesn’t show up in the list of markers below the map. I can’t select it to edit it. I tried adding a 6th marker to replace the one that I couldn’t edit, but I get the same thing. What happened?

https://ww.wp.xz.cn/plugins/google-maps-easy/