A study I want someone to do

This study found heart issues @Jonathan Edwards
Paper : Impaired cardiac function in chronic fatigue syndrome measured using magnetic resonance cardiac tagging
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3627316/

If I understand right by referring to the text of the study, radial thickening is a thickening of the heart wall. This particular effect is also noted with people suffering Mitochondrial Complex V dysfunction (similar dysfunction perhaps to that Paul Fisher has identified).
https://ghr.nlm.nih.gov/condition/mitochondrial-complex-v-deficiency

Did I interpret that right?

 

At least one study suggests PWME do much worse on tasks involving multi-tasking - perhaps that's the issue?

 

@Marco, @Subtropical Island, "multitasking" tasks are pretty sensitive to all kinds of general cognitive problems, so yes, you'd expect them to be difficult for PwMEs. But while sensitive, they're not that specific, so they don't give us a lot of clues as to what the exact problem is.

What @Subtropical Island describes is interesting though. Your problem on the task doesn't sound like a "memory" problem per se, at least not in the sense in which we normally think of memory - remembering past events - because the brain regions that support that kind of memory are not needed for the kind of task you're talking about here. It could just be that the high demands of the task lead to occasional cognitive overload, which makes you feel suddenly frozen, like you can't remember what to do.