WDS mode WiFi client roaming issue

So I've got two TP-Link Archer A7 v5 routers where one is the main router/gateway running WDS AP mode and another running in WDS Client+AP (repeater mode).
FIOS ONT <---> TPLink A7 WAN (Router, LAN DHCP Server, 2.4GHz/5GHz AP in WDS modes) <-wireless-> TPLink A7 (LAN DHCP disabled, Static LAN IP, STP Enabled, DNS Forwarded to Main router, 5GHz is STA+AP and 2.4GHZ is AP, all WDS)
This is how it was setup: https://openwrt.org/docs/guide-user/network/wifi/atheroswds
All seems to be working as expected, except one thing.
The problem happens when a WiFi client once connected to the Main Router now all of a sudden attempts to connect to the WDS STA+AP's AP.

For example, lets assume my mobile phone is initially connected to the main router's 5GHz band. Everything is great. Now, I turn off the WiFi on my mobile phone, go very close to the Dumb AP and switch on the WiFi. I see the network being broadcasted using the same SSID from the Dumb AP, the signal is super strong. However, the phone sits there in configuration state obtaining IP address for quite some time. The only way to fix it is to keep the WiFi on said mobile phone off for a stretch of time (now that could be about 5 minutes or so but I have never really calculated this interval). After said amount of time has elapsed, if I switch on the WiFi on the phone, it will receive an IP address instantly.
Just to set expectation, when I was on Chaos Calmer, I didn't experience this issue (although I have to say I was using different routers then).

Is this normal or is there some setting that allows for the latter connection from the DumbAP to receive the IP without a hitch. I'd rather not keep the mobile phone off for a few minutes to get the IP.

Any advice?

The issue remains, between different and the same hardware. What I find is that this only happens with the radio which operates the backhaul STA. When you roam to the extender's 2.4 GHz radio, which is not running the WDS STA mode, the issue seems not to be happening...