Problem: When I add an IP address range to the list and save settings I get the conflicting messages "Settings successfully updated" and "The plugin was unable to write to the .htaccess file. Please edit file manually." The .htaccess file settings are 0644 as recommended in the Filesystem Security section.
This is not a big deal - I am quite happy to edit the .htaccess file. However, the entries there use CIDR /n notation (Deny from 18.104.22.168/24) where the corresponding entry in the Blacklist Manager uses * (176.103.228.*). It might be better if Blacklist Manager also used /n notation, which would then allow ranges other than class A, B or C - I have put in a couple of /21s and a /18 (people from republics with names ending in stan, and similar far-flung places, really have no business trying to log in to administrator accounts on my site).
Feature request: it would be useful, when I look at the failed logins records, if there was a bulk action to add to the blacklist