works fine with any Custom Field, it does not matter if a new, old or even if Types / Not Types Field
The WordPress function will always fetch the Field that you tell it to fetch.
So it must be a issue with your Post ID, or the Field Slug, or what it returns.
I can not see how this is setup, and we do not provide Custom Code Solutions or debug in the Free Types Forum.
What is as example returning this below code?
I do not see in your code how you define this $child_post variable and that is crucial for you to analyze so to be sure the ID is the correct one.
You also pass 'false' to your Custom Field get_post_meta(), so it will not return a single value.
If you analyze your Source code you will see, no URL is passed to the img src, it is left out empty.
Also href is empty.
Means, your
is returning nothing.
This can not be due to just adding a Field with types that is not related to your content.
It's not possible because if the field is not related, and not queried in $floorimg, it can also not interfere.
Unless of course, the field has the exact same slug as the queried one and belongs to the same post ID.
But as mentioned, this is Custom Code and can not be debugged by us in this Free Forum, where we support the Free Types Plugin and it's features.
To design Content created with types you can either user the Provided ShortCodes, or, you can use Views and Content templates, which should allow you to do pretty much the same you do now with PHP; but all from within the WordPress Admin, with no PHP.
https://toolset.com/home/toolset-components/
https://toolset.com/documentation/user-guides/view-templates/
https://toolset.com/documentation/user-guides/views/
If you need assistance with Custom PHP Code you can consult the DO Cfor the Types API:
https://toolset.com/documentation/customizing-sites-using-php/functions/
https://toolset.com/documentation/user-guides/displaying-wordpress-custom-fields/#1
Also, we can recommend the certified partners in case you need more assistance with Custom PHP:
https://toolset.com/consultant/
You will get the custom assistance you need to get on with your project.
Thank you for understanding.