No worries.
@peternlewis Can you explain how the "Quick Macros.plist" file is laid out? Specifically, how do I know which part contains the most recent recording? I thought I knew the answer to this, but apparently I'm not right, at least not all the time.
I'm sure you already know this, but I know how to read your plist files, so you don't have to go into too much detail. 
There is no way to know what the most recent recording is.
Currently (absolutely undocumented and subject to change at any time), the file is a mapping from UID to action array.
The UID is stored in the Record Quick Macro action - you can have more than one, and each should have a unique UID.
How do you determine which macro to run when I press Opt+F1?
Based on the Record Quick Macro action, which defines both the UUID and the hot key.
Each Quick Macro action has its own independent recording.
OK, that helps. Thanks.
But there's only ever one macro that can be launched with Opt+F1. (I assume the others are from when I record a macro while editing a macro, right?)
So which one is the one Opt+F1 will execute?
That older UUID, within the Quick Actions.plist, will not be overwritten no matter how many quick macros I record, no matter if I delete it or modify it. I has 9999 lives. 
Yes, basically, if you create a Quick Record action and record a macro, and then delete that action, the recording will likely be saved forever and do nothing.
I've just uploaded version 2.0 in the original post, which hopefully solves the problems the prior version had.
Let me know how this works for you. Thanks.
@DanThomas - You are still battling this. Much respect to you. It looks like you figured something out. However, I get this error.
The picker did see 6 UUIDs and the %Variable%Local_UUID% does change with each selection.
Thank you!
Never say die! 
Can you zip up your Quick Macros file and send it to me via PM? The file is at:
~/Library/Application Support/Keyboard Maestro/Quick Macros.plist
Thanks!
You are definitely a trooper and we are lucky to have you here (me especially).
What OS are you using? I can't duplicate the error on either Catalina or Monterey.
Big Sur. 11.6.2
I'll take a look at it tomorrow. I'll have to send you some test code.
I just uploaded version 2.0.1 in the original post. Please delete your existing "Import Quick Macro" macros, download and install the new version, and see if it fixes anything.
I actually don't think it'll fix your problem, but it does fix a bug I found, and I learned a long time ago to fix any bugs I can find, even if they don't appear to be related to the specific issue I'm trying to solve. You'd be amazed how many times this solves the supposedly unrelated issue.
Let me know. Thanks.
Thanks Dan. However, the error still remains while running the Import Quick Macro and running the Import Quick Macro Picker.
I even tried it on a different machine, running KM 10.0.2, but it didn't work at all (didn't even through the error). Sorry to the report negative news.
Thanks,
KC
Are you saying you're not running KM 10.0.2 in your current machine?
As far as the second machine not throwing an error, did you remember to enable the group/macro?
I'm saying both machines are running KM 10.0.2. My main machine is running Big Sur but the older test machine is running High Sierra. All groups and macros are enabled on both.
Here is what is weird though. I just ran a test using the second Import Quick Test Macro that you posted, works fine on the older High Sierra machine. The new Import Quick Macros 2.0.1 doesn't. So, I'm deducing that it is my main machine at this point or it's some secret sauce somewhere. 
Edited to add: The Import Quick Test Macro still works on the main machine but it still creates that original macro that has the 99 lives.
I really appreciate all you're doing to help. It means a lot.
This next part is going to sound like I'm a teacher hitting your knuckles with a ruler, but I don't mean it that way. Like I said, I'm thrilled you're helping.
Please be more specific when you talk about what works and what doesn't, because I'm starting to get confused. If it displays an error message, then say that. If it doesn't appear to do anything and doesn't display an error message, then say it doesn't seem to do anything.
Also, let's stick with the latest version (2.0.1). Referring to older versions also confuses me (as you can see, confusing me is a simple task).
But do I understand correctly that on one of your machines, it doesn't appear do anything? No error message? Because if that's the case, it most likely means that the macro tried to import something, but KM didn't like the format, so it ignored it. Which means it actually got further than the ones that display an error message.
So, go ahead and answer these questions, and when I'm un-confused, I'll give you something with logging that hopefully will help.
Ok. How about I stick to the main machine as I was trying to perform due diligence testing on the other.
The Main Machine, with Big Sur 11.6.2, KM 10.0.2 and the Import Quick Macro 2.0.1 still throws this error:
