This is a known issue and we are working on a fix.
To give you some background, the issue is happening because by default Joomla & all 3rd party extensions use the default Boostrap 2 modal but since Astroid is based on Bootstrap 4. It's breaking things and conflicting with them a bit.
We hope to have a fix soon.
If you like our support and products, tweet us at joomdev and let the world know about it.
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