Thanks for your testing. On High Sierra, the Menu bar is lost in the following apps using Japanese version of MacOS; 1. Oxygen Editor (latest version) 2. iMindMap 10 (latest version) The other apps the menu bars appear normal and function well on my Mac are; All the rest including, 1. FilemakerPro A...

Thank you for your prompt response.

I restarted the OS. The result the same - Menu bar remains lost...

Huu...m,
I does not seem working in MacOSX in Japanese.

Oxygen Editor:
<key>CFBundleAllowMixedLocalizations</key>
<false/>

In my case, the language is Japanese and version of Oxygen Editor is as follows;
Original release date: April 5, 2017
Build id: 2017062918 RSS
Build date: June 29, 2017
Size: 230MB

No multi-displays.

I too had the same problem of losing menu bar in High Sierra (version 10.13) as of 27 Sep 2017. This happens on Oxygen Apps ( tried only two Editor or Author) . The other third party apps work OK so far. My mac is: MacBook Pro (13-inch, 2017 Four Thunderbolt 3 Ports) 3.1 GHz intel Core i5 16 GB 2133...