Ok, so it appears to be the data that's goofy. I re-ran your code snippet and it worked just fine. When I run that on my data I get the error "/ must follow a numeric type" which according to diagnostics is "(F) You had an unpack template that contained a '#', but this did not follow some numeric unpack specification. See perlfunc/pack.". That's an unhelpful error (to me anyway). I had misinterpreted that to be a compile-time error so didn't even think that the unpack format was valid.

Now I'm stuck with a blob of data that doesn't appear to unpack correctly. I tried cutting bits off from the end and oddly - it works sometimes though not consistently from different contexts. The behaviour is so bizarre that I'm just going to have to write a better test for it to tease out where either I'm going wrong or perl is buggy. When I know something further I'll post to this or a new thread later.

__SIG__
printf "You are here %08x\n", unpack "L!", unpack "P4", pack "L!", B::
+svref_2object(sub{})->OUTSIDE
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