Thank you for your quick reply. This might be simple to do temporarily, by removing filtering on the text. That is, you have a simple input field for text that normally needs to be sanititized. For now, if we can paste in the HTML source for a Group block (wrapped in comments) then that might render in the UI. I wouldn’t mind the extra step. Or tell us if we can drop in your block, edit source, and paste in a nested block/group.
Honestly, when I couldn’t do this with your plugin I instantly went to Shortcodes Ultimate which does the same job plus a hundred more, and I was able to accomplish this immediately. Sorry for mentioning a competitor, but as developers we’re all struggling to create something that is unique and useful for our audiences.
I hope that helps. Best to you.