Yeah this is a messy one, I think only the oneboxer and frontend bug:
https://frinklang.org/fsp/solve2.fsp?equations=a+%2B+b&solveFor=&f=&ev=on
vs:
<https://frinklang.org/fsp/solve2.fsp?equations=a+%2B+b&solveFor=&f=&ev=on>
vs:
https://frinklang.org/fsp/solve2.fsp?equations=a+%2B+b&solveFor=&f=&ev=on
I have a fix here, but as you can see from Related topics, this is VERY COMPLICATED 
, over the years there have been so many bugs in this area.