(?!^) is not handled correctly by Regex framework

[DJBen]

Description

"dispatchWithName".matches(of: /(?!^)(With(?!No)|For|In|At|To)(?=[A-Z])/)

returns 0 matches, but Regexr shows there should be one match

Reproduction

"dispatchWithName".matches(of: /(?!^)(With(?!No)|For|In|At|To)(?=[A-Z])/)

returns 0 matches

Expected behavior

"dispatchWithName".matches(of: /(?!^)(With(?!No)|For|In|At|To)(?=[A-Z])/)

should return 1 match "With"

Environment

Verified Xcode 16.0 is fine; appeared in Xcode 16.3

Additional information

No response