Interesting! I do not have that checked (I never use them). Yet
Code:
v:\> echo foo %+ echo bar
foo
bar
And I see (the expected?)
Code:
v:\> echo %=foo
%=foo
Enabling their expansion has no effect on the %+ behavior mentioned above, but gives this.
That first character is the character I see if I "ECHO %@CHAR[12]".
Pseudovariables have been deprecated for three years and are officially unsupported in v20. They might still appear to work in a few cases, but that could change at any time.