bsorli i have had a simular problem and turned out i was still using a very old plugin.
Here is my answer on the post i made a month ago as a premium ticket:
Just found out that i had installed "System - JA Content Type" and when i disable that plugin, i CAN see the import page as it should. That plugin was used a very long time ago by me and is now used anymore on the site, so i can disable it. It all seems to work fine now, so ticket can be closed.
I have installed version 1.1.4 of the "System JA Content Type" plugin.
Perhaps this helps....