Very interesting.
By me cmd "nvram get nmp_client_list" gives empty output, but file /jffs/nmp_client_list exists and the size is > 0.
ls -l /jffs/nmp_client_list
-rw-rw-rw- 1 root root 735 May 18 20:27 /jffs/nmp_client_list
The file /jffs/nmp_client_list contains only part of my wifi...
The issue with section "View List' under the Network Map is caused by a defective list in "custom_clientlist".
Please enable ssh and reset the nvram parameter custom_clientlist:
nvram set custom_clientlist=
nvram commit
I had the same issue.
Solution:
1) backup macfilter in ASCII format (TXT)
2) activate ssh daemon
3) login
4) nvram show| grep maclist
5) clear all macfilters for all wlan interaces ("nvram set wl[|0|1]_maclist[|_x]=")
6) nvram commit
7) reenter all required macfilters from GUI