There is a typo in the plugin code that prevents the added id from being saved.
There is a single line that says:
Code:
tree_modified = True
that needs to be changed to:
Code:
file_modified = True
Plus some needed related fixes as well.
This will be fixed tomorrow when I release a beta quality version of the plugin. Then for your pattern the id will be added to the svg tag and all links will work as is with no changes on your part. But that said, putting your own id on the svg tag instead of the figure tag, will work around this issue until the fix is released.