The option to hide intro text means hide it in the full article.
This is useful when you want to create an intro text for the category view that is different in the full view.
One method to hide the intro text from blog layout is creating an override in your template. Follow these steps:
1.- Copy file from components/com_content/views/category/tmpl/...
There is something you can do by combining the available abilities in Joomla core, but there are certainly many other custom ways to achieve this.
Of course it depends on how you want to use this and what you want to achieve, which you haven't clearly specified.
Do you want to save this in the database? Simply show it on your blog layout? or in modules?
The show intro text is meant for the article view not the blog layout. With hide intro text you can have a special intro text for your article, that can be hidden when you go to read the full article in the article view.
You can alway create template overrides to create any special layout you want.
If you search you can find many resources about creating ...
I've had a very similar problem. If Article Newsflash Advanced was displayed inside a tab from Bootstap Tabs module, then you have to open Item Settings tab of this module and set Show Content Images setting to Yes.
If you can still find the image that you added to the introtext, when you open the article to edit with the editor, then the image isn't getting stripped from saving into the database.
Now, the information you provided is not clear and sufficient. For example we don't know what you are using to display the articles / where you are expecting to see that ...
At the time we don't have an automatic feature for this in the core, you can do this manually by adding one by one in your content or you can add a custom code via override for the blog layout.
Also you can try with one extension in order to automate more this process, here you have two possible options:
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