Hello!
I've the same issue but not only on ax3. I'm using 2 capAX, 1 ax2 and 1 ax3 with capsman.
If only one SSID is activated on 2.4ghz interfaces, everything is okay, all client (~40) are connected and they have stable connection.
If the second SSID is also activated (master + slave cfg), clients keep disconnecting from both network. In this case I've the same log entries like ssaliba.
Working Capsman cfg (only one 2.4 SSID):
/interface wifi channel
add band=2ghz-ax disabled=no name=channel-2ghz skip-dfs-channels=10min-cac width=20mhz
add band=5ghz-ax disabled=no name=channel-5ghz skip-dfs-channels=10min-cac width=20/40mhz
/interface wifi datapath
add bridge=bridge1 disabled=no name=datapath-intra vlan-id=10
add bridge=bridge1 disabled=no name=datapath-restricted vlan-id=20
add bridge=bridge1 disabled=no name=datapath-guest vlan-id=30
/interface wifi security
add authentication-types=wpa2-psk,wpa3-psk connect-priority=0/1 disabled=no ft=yes ft-over-ds=yes name=sec-intra wps=disable
add authentication-types=wpa2-psk connect-priority=0/1 disabled=no ft=no ft-over-ds=no name=sec-restricted wps=disable
add authentication-types=wpa2-psk,wpa3-psk connect-priority=0/1 disabled=no ft=yes ft-over-ds=yes name=sec-guest wps=disable
/interface wifi configuration
add channel=channel-5ghz country=Hungary disabled=no mode=ap name=cfg-intra-5ghz security=sec-intra ssid=Intra
add channel=channel-2ghz country=Hungary disabled=no mode=ap name=cfg-intra-2.4ghz security=sec-intra ssid=Intra
add channel=channel-2ghz country=Hungary disabled=no mode=ap name=cfg-restricted-2.4ghz security=sec-restricted security.ft=no .ft-over-ds=no ssid=\
Restricted steering.rrm=no .wnm=no
add channel=channel-2ghz country=Hungary disabled=no mode=ap name=cfg-guest-2.4ghz security=sec-guest security.ft=no .ft-over-ds=no ssid=Guest
add channel=channel-5ghz country=Hungary disabled=no mode=ap name=cfg-guest-5ghz security=sec-guest security.ft=no .ft-over-ds=no ssid=Guest
/interface wifi capsman
set enabled=yes package-path=/ require-peer-certificate=no upgrade-policy=suggest-same-version
/interface wifi provisioning
add action=create-dynamic-enabled disabled=no master-configuration=cfg-restricted-2.4ghz supported-bands=2ghz-ax
add action=create-dynamic-enabled disabled=no master-configuration=cfg-intra-5ghz supported-bands=5ghz-ac
NON-working Capsman cfg (two SSID on 2.4)
/interface wifi provisioning
add action=create-dynamic-enabled disabled=no master-configuration=cfg-restricted-2.4ghz slave-configurations=cfg-intra-2.4ghz supported-bands=2ghz-ax
add action=create-dynamic-enabled disabled=no master-configuration=cfg-intra-5ghz supported-bands=5ghz-ac
I played with Steering, Connect priority, Channel band, Channel width without success.