I think there might be a bug in the latest pxt-blockly release or it might be something I am doing.
When I import the compressed files, this is what I get 
Hopefully someone can point me to a fix
we’ve recently updated to the latest version of Blockly with their “Zelos” rendering, so you may want to check their release notes: https://github.com/google/blockly/releases/tag/3.20200123.0
additionally, make sure you’re passing renderer: "pxt" in the options for any calls to Blockly.inject()