It shouldn't matter and still should work. Have you clicked the refresh button in the upper right corner of the ban list and see if that doesn't the job? Also, look in the console window and you should see the request made, and the response from the server. If you do, please copy/paste that console log here and I'll look into it and see if I can figure out whats going on.
Another User here, but the same problem, perhaps my log will still help:
2017-04-13 16:04:16 35460.401 INF Executing command 'ban list' by Telnet from 95.xx.xxx.231:64868
2017-04-13 16:04:12 Ban list entries:
2017-04-13 16:04:12 Banned until - SteamID - Reason
2017-04-13 16:04:12 3/18/2018 2:47:09 AM - 7656119xxxxxxxx61 - stealing
2017-04-13 16:04:12 3/19/2018 12:19:26 AM - 7656119xxxxxxxx03 - asshatting
2017-04-13 16:04:12 3/20/2018 9:12:30 PM - 7656119xxxxxxxx47 - wth
2017-04-13 16:04:12 3/22/2018 8:13:18 PM - 7656119xxxxxxxx42 - advertising
2017-04-13 16:04:12 3/25/2018 11:30:26 PM - 7656119xxxxxxxx56 - asshatery
So the data is there, the Ban list stays empty though.