I apologize for frustrating you.
If it makes you feel better, I threw my back out and am in considerable pain. Feel free to enjoy a moment of schadenfreude.
At risk of annoying you further, I have, as you suggested, tried it out and… it worked. The original choice came up and the Process Images workflow executed properly every time the script looped. I repeated this many times, but did not reproduce your problem. There were some quirks, but they were a result of how I tested this, not bugs.
This is what I did (the simplified version - there were intermediate steps in which I had a third workflow, reopened and resaved, etc.)
First, a workflow called “Process Images Test Workflow” with two actions:
1 - Run AppleScript (the script)
2 - Run Workflow (Process Images Test Workflow) - you can see why intermediate steps were involved.
Second, an application called “Process Images Test Application” with two actions:
1 - Run AppleScript (the script)
2 - Run Workflow (Process Images Test Workflow)
I launched the application, chose “Process Images”, which became the frontmost process, and as soon as that started the application icon started bouncing - I had to click the icon to bring the next “Choose a workflow to run” window to the front. Minor tweaking would fix that, but this is only a test so I didn’t bother.
I’m going to keep a copy of Jacques script handy, it might be useful to me in the future. Although you already solved your problem, maybe my suggestion will be useful to you at some point.
j