widgets.php: Only a maximum number of 25 dynamic sidebars displayed

Hi Daniel,

after updating WordPress to its most recent version 4.4.1 I’m experiencing several problems:

Whereas the 500 server errors when opening the sections customiser and widgets in the backend could be solved by disabling certain plugins, one problem persists:

I’m using a lot of custom dynamic sidebars on my blog, probably about a hundred or even more. Unfortunately, in the widget section only the first 25 are shown: https://drive.google.com/file/d/0B_SwBoaHOYXUV28ycmQxRTk0dXc/view?usp=sharing

Is this a memory limit related issue? I already increased the memory limit in the wp-config.php to 265MB. Also disabling all plugins didn’t solve this problem.

I’m happy about any advice you can offer me!