Fetching core… doesn't ends

When I run a scan, at the point: Fetching core, theme and plugin file signatures from Wordfence never ends. I always kill the scan after about 20 min., now.
As it gets this info from Wordfence, I guess it cant’t be a problem with the settings. Although I tried to set down the memory limits and timeouts, but this also doesn’t work.
Maybe a problem with a installed plugin? I don’t know. Is there a know issue?
What can I check more to get it work?

https://www.ads-software.com/plugins/wordfence/