accordions can’t move single accordion

I have an accordion with 15 items. I wanted to change the item order and move the last item to the top and noticed that if I click on the last item to move it I always will move the last 8 items together, it's not possible to move one single item of the last 8. With the first 7 items on the top all working fine, I can move a single item, but the last 8 are fixed into a kind of a closed block. The problem's occuring in firefox and graphically even worse in chrome. On server latest php and mysql versions running...

Maybe there is something with following error notices which I get with firefox inspector:

ReferenceError: reference to undefined property "returnValue"
[Weitere Informationen]
load-scripts.php:3:15422
TypeError: a is undefined
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tinymce.min.js:28:8926
load-scripts.php:4:21019
ReferenceError: reference to undefined property "traditional"
load-scripts.php:4:25067
ReferenceError: reference to undefined property "username"
load-scripts.php:4:26273
ReferenceError: reference to undefined property 200
load-scripts.php:4:20474
ReferenceError: reference to undefined property 0