Syntax highlight getting lost when jumping down large file

I am writing a book using Asciidoc format. You can find the Asciidoc file here:https://github.com/krlawrence/graph/tree/master/book

I am using MacVim version: 8.0.1420

I have not noticed this problem as much in earlier versions of MacVim and it is not an issue editing the same file on Windows using Gvim.

If I load the file and set the syntax to Asciidoc the highlighting looks fine. However if I then do a search that requires jumping way down the file or if I just manually jump to the end of the file, syntax highlighting is lost. Doing a syntax sync fromstart does not bring it back and setting the syntax back to Asciidoc again only seems to work if I jump back to the top of the file and manually scroll down the file. As soon as I jump down the file again same problem. This seems to have started happening since I updated to this version of MacVim.

My OS is MacOS 10.13.3

I have sometimes seen this behaviour before but never until now encountered a case where doing a syntax sync fromstart does not fix it.

Beginne damit, den Bericht mit der Asciidoc-Datei im verknüpften Buchverzeichnis unter Verwendung von MacVim 8.0.1420 auf macOS nachzustellen. Vergleiche die Syntaxhervorhebung nach dem Laden von Asciidoc, dem Springen ans Ende, dem Ausführen von syntax sync fromstart und dem Scrollen vom Anfang. Als erledigt gilt dies, wenn die Hervorhebung nach großen Sprüngen korrekt bleibt und der gemeldete Synchronisierungsbefehl wie erwartet funktioniert.