If trying to find NavLinkProxy with SimpleLink and SmartLink enabled by searching the path, sometimes CustomLink is not found (CustomLinkId=0). Since only one NavLinkProxy is located on the level, we expect it to always be found. Depending on where you start your path search, you may be able to find a NavLinkProxy. If CustomLinkId is not found, we can find it by deleting SmartLink.
Not find Custom Link and output error log "Not found Custom Link"
Find CustomLink and output log "Success"
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-157200 in the post.