Hi @carola,
In your OJS installation directory, do you have commit 9a38b0ae3ed932663bb5a92c8c747e4a31757651 included? (See e.g. git log js/pkp.min.js.)
The difference between minification enabled and disabled is that when minification is enabled, OJS relies on js/pkp.min.js to contain all its Javascript. When minification is disabled, OJS goes to the dozens of individual js files instead. If changing the flag to On breaks things, then it sounds like your compiled javascript is out of date (or an old version is cached).
Regards,
Alec Smecher
Public Knowledge Project Team