PlantUML not working, CORS error

[Michael Jones]

When trying to insert a diagram into a confluence (hosted) page, I get this error:

Access to XMLHttpRequest at 'https://exp-plant.draw.io/plantuml4/png/.............

macroEditor.html?dialog=1&simpleDialog=1&xdm_e=https%3A%2F%2Fmeshplusplus.atlassian.net&xdm_c=channel-com.mxgraph.confluence.plugins.plantuml__plantumlcloud&cp=%2Fwiki&xdm_deprecated_addon_key_do_not_use=com.mxgraph.confluence.plugins.plantuml&lic=none&cv=1.527.0:1 Access to XMLHttpRequest at 'https://exp-plant.draw.io/plantuml4/png/.........................' from origin 'https://puml4cc-116.appspot.com' has been blocked by CORS policy: The 'Access-Control-Allow-Origin' header has a value 'https://exp-plant.draw.io' that is not equal to the supplied origin.

Is this a known issue? Any work arounds?

[Andy Nightingale]

I get the same error on Confluence Cloud.  Different URLs but with PUML.  As things stand, the plugin is useless.