ä,ü,ö not working

Hello, I have one major problem with the accordions plubin:

I have a German Website and when there are ä,ö,ü,ß etc. in the accordions-head-title i get the utf8 encoding for the letter e.g. ä when i change the utf8 code to an ä the ä shows up for the first time, but when I save for a second time the utf8 code shows up…

In the Content section i do not have these problems.

Are there any solutions for the problem?

URL: http://www.mhlick.com/knoll/referenzen/

Accordions Version: 2.0.8

https://wordpress.org/plugins/accordions/