I didn't know that each plugin had it's own tag on this Q&A. It's not really monitoring friendly here, either, we can't get emails when tags are used, so if you could favour the github issues tracker, https://github.com/jgraph/diagramly-confluence/iss
We did fix the issue and have a release out 2 days after finding out, we just didn't know about this post...
Having the same issue, this plugin is so promising.
I feel that the only solution is for the developer to fix it or someone to jump into the sourcecode on gitub and fix it. Though the original developer must submit the new version to the store I think.