In the lesson "Fact or Fiction" , on my daily review, the sentence "how about we go for a walk" poses a problem to me. I would say "how about going for a walk.
I've found examples with the construction "how about we- make, go, start..." showing that it's grammatically correct.
You like "how about going" better?
The difference between the two could be that the second -how about going- is less specific about WHO would go for a walk: it's not obvious that the speaker would come along whereas the first form is clear about that, it's a proposition we go, you and me.
That was not a swift answer, sorry about that, you must have noticed that the access to this forum IS NOT easy to find, I was told by one of the gymglish team it was a bug to be fixed, but it seems to continue.
I hope it helps anyway,