Hi Ciaran

I have an issue with J51_Stella when editing in the Front-End an selecting an Intro Image or a Full Article Image:

- go to the Front-End and login
- open any article or create a new one
- go to the «Images and Links» tab
- click «Select»
- the screen will be darkened but no dialogue appears.

It happens with both Firefox and Google Chrome.
It does not happen when I insert an image into the article text using the editor button.

I can see that somone reported this kind of issue earlier:
https://www.joomla51.com/forum/intro-image-on-frontend

The solution you suggested here https://www.joomla51.com/forum/intro-image-on-frontend did resolve my issue.
I think that this issue is template-related and should be amended in general.

Thank you and kind regards
Chris