FCMP function giving unexpected results in PROC SQL

I wanted to take Rick Wicklin's macro (https://blogs.sas.com/content/iml/2015/10/05/random-integers-sas.html) that generates random numbers and convert it into an FCMP function. The FCMP function works as expected when called using %sysfunc(randbetween(1,100)); or via a data step, but from proc sql it always returns a value of 1.

proc fcmp outlib=work.funcs.funcs;
  function randbetween(min,max);
    return ( min + floor( ( 1 + max - min ) * rand("uniform") ) );
  endsub;
run;

Working example:

data example;
  do cnt=1 to 1000;
    x = randbetween(1,100);
    output;
  end;
run;

Broken SQL example:

proc sql noprint;
  create table have as
  select randbetween(1,100)
  from sashelp.class
  ;
quit;

Is this a bug? Or am I mis-using something?

SAS version is SAS9.4TS1M5. Windows 10x64.

EDIT: When I subsitute the formula directly into the SQL statement it works as expected, so it seems unrelated to the call to rand("uniform").