I've reset to a blank config on the CRS125 and configured things as seen below, where ether1 is my uplink from a Ubiquiti EdgeRouter, and then the rest of the ports are all switched. In other words ether2-ether24 are slaves to ether1, and ether1 and wlan1 are bridged.
Flags: X - disabled, R - running, S - slave
# NAME MTU MAC-ADDRESS ARP MASTER-PORT SWITCH
0 RS ether1 1500 D4:CA:6D:FA:6F:1E enabled none switch1
1 S ether2 1500 D4:CA:6D:FA:6F:1F enabled ether1 switch1
2 S ether3 1500 D4:CA:6D:FA:6F:20 enabled ether1 switch1
3 S ether4 1500 D4:CA:6D:FA:6F:21 enabled ether1 switch1
4 RS ether5 1500 D4:CA:6D:FA:6F:22 enabled ether1 switch1
5 RS ether6 1500 D4:CA:6D:FA:6F:23 enabled ether1 switch1
6 RS ether7 1500 D4:CA:6D:FA:6F:24 enabled ether1 switch1
7 RS ether8 1500 D4:CA:6D:FA:6F:25 enabled ether1 switch1
8 RS ether9 1500 D4:CA:6D:FA:6F:26 enabled ether1 switch1
9 RS ether10 1500 D4:CA:6D:FA:6F:27 enabled ether1 switch1
10 RS ether11 1500 D4:CA:6D:FA:6F:28 enabled ether1 switch1
11 RS ether12 1500 D4:CA:6D:FA:6F:29 enabled ether1 switch1
12 S ether13 1500 D4:CA:6D:FA:6F:2A enabled ether1 switch1
13 S ether14 1500 D4:CA:6D:FA:6F:2B enabled ether1 switch1
14 S ether15 1500 D4:CA:6D:FA:6F:2C enabled ether1 switch1
15 S ether16 1500 D4:CA:6D:FA:6F:2D enabled ether1 switch1
16 S ether17 1500 D4:CA:6D:FA:6F:2E enabled ether1 switch1
17 S ether18 1500 D4:CA:6D:FA:6F:2F enabled ether1 switch1
18 RS ether19 1500 D4:CA:6D:FA:6F:30 enabled ether1 switch1
19 S ether20 1500 D4:CA:6D:FA:6F:31 enabled ether1 switch1
20 RS ether21 1500 D4:CA:6D:FA:6F:32 enabled ether1 switch1
21 XS ether22 1500 D4:CA:6D:FA:6F:33 enabled ether1 switch1
22 XS ether23 1500 D4:CA:6D:FA:6F:34 enabled ether1 switch1
23 XS ether24 1500 D4:CA:6D:FA:6F:35 enabled ether1 switch1
24 sfp1 1500 D4:CA:6D:FA:6F:36 enabled none switch1