In my original experiment I mistaken created a connection reference that was longer than 1 character.
<Connection Name="Input" AllowMultiple="False" Optional="False" Type="Connection" Label="LONG_EXPRESSION_HERE"/>
After updating the code to "I" or "", Alteryx still complains on load:
Javascript plugin error: Connection label must be exactly one character
And the existing Python example is failing, suggesting some kind of corruption.
I wonder if the internal python code cache needs to be cleared... How?
Using Alteryx 11.7 now.