The scenario letters and domino icons show up and work fine when I start the Web app from scratch. But when I load a (current version) existing rule file, the letters and domino icons disappear. And sometimes the logic gate won't load.

Initially I can open "Metadata", then when I try to open the "Logic Gate" I get nothing; then when I try to open "Metadata" again it won't load.

A recent .json export file is attached.