I have this problem and have been experiencing the same thing since I started using iterm / zsh in October 2016. This happens both on my work laptop and on my personal laptop (I have almost the same setup for both). This is only a problem in iterm - a regular Mac OS terminal works just fine.
I am currently using iterm build 3.1.5. and also have a layout in German.
This is annoying, but I recently found out that CTRL + ALT + 9
does the job.
I would be interested to know about the correct fix.
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