@Bmosbacker And please note that HTML and filenames often have trouble with spaces. Spaces and natural language in filenames and code are a nicety that Apple offers us but that do not work in the wider computer world. See coding for the web. See various flavors of UNIX operating systems, as well as many other computer frameworks, languages, platforms, and systems.
Being an experienced user in the Apple world often is poor preparation when you begin playing behind the scenes.
That probably explains why I’m having these difficulties. I don’t want to spend much time tweaking the syntax of a name to embed an image. The code blocks work great in iA Writer, but I was hoping I could click on a file and copy its file path and embedded it in iA Writer and it would work across markeddown editors. But that does not seem to be the case. At least not without a lot of additional tweaking with periods and dashes. For my purposes, that would not be a good use of my time. A little too much friction for this non-coder. 
IA Writer support responded to my support request. Here is the response:
Hi Barrett,
Thanks for reaching out to iA Support.
That file path syntax won’t work and isn’t cross platform compatible anyway.
You can use Markdown syntax. Links need to be URL/percent encoded. The easiest way to get the correct syntax is to use the contextual Copy Markdown option on a Content Block to get the correct Markdown syntax:
[NOTE: Support included a GIF of the process, but I cannot post it to MPU. Below are two screenshots from that gif]
You can do this on Mac. There is a known issue with this workflow on iOS/iPadOS at the moment, but it should be resolved in the future.
Please feel free to give that a go and see if it works for you.
Warm regards,
J.
Information Architects
Tokyo
This is a helpful response and is appreciated, but because I use my iPad for a significant portion of my writing, this is less than ideal. I don’t know how far “in the future” I will have to wait for the workflow to be resolved, but experience tells me it will take longer rather than sooner.
