[racket] for/and unhappiness with 'not' and the definition of Booleans?

I'm unable to get for/and to typecheck when the body is an application of 'not'. I've tried many variations on the following, without success:

#lang typed/racket

(for/and: : Any ([i (in-range 4)])
  (not (my-pred)))

(define (my-pred)
  #f)

=> 

Type Checker: Expected True, but got Boolean in: (for/and: : Any ((i (in-range 4))) (not (my-pred)))


The error message suggests that the body must have type "True", though I suspect this is a consequence of if-splitting somehow.

Any suggestions or improvements to error messages appreciated.

John

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