NavigateToFunctionSource error help

when compiling an Animation Blueprint, i get this error:

Warning: NavigateToFunctionSource:  Didnt find source file for [AFPSCharacter::IsPlayerAiming] - File [D:\build\U5M-Marketplace\Sync\LocalBuilds\PluginTemp\HostProject\Plugins\FPSCore\Source\FPSCore\Public\FPSCharacter.h], Line [111], Column [0]

heres the pastebin code of FPSCharacter.h

can anybody help?