2.4Ghz radio problems since 19.07.2 upgrade on Meraki MR18

Since upgrading to OpenWrt 19.07.2 r10947 my 2.4 Ghz radio in my MR18 keeps going down and then becoming available again after a while.

Issue has persisted through a system restart

Kernel logs around the time the radio is shutting down:

[181740.257001] device wlan0 left promiscuous mode
[181740.261835] br-lan: port 3(wlan0) entered disabled state
[181741.506440] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
[181741.601164] br-lan: port 3(wlan0) entered blocking state
[181741.606686] br-lan: port 3(wlan0) entered disabled state
[181741.612513] device wlan0 entered promiscuous mode
[181750.149736] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[181750.156453] br-lan: port 3(wlan0) entered blocking state
[181750.161998] br-lan: port 3(wlan0) entered forwarding state
[181760.277999] device wlan0 left promiscuous mode
[181760.282846] br-lan: port 3(wlan0) entered disabled state
[181760.849533] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
[181760.907222] br-lan: port 3(wlan0) entered blocking state
[181760.912820] br-lan: port 3(wlan0) entered disabled state
[181760.918672] device wlan0 entered promiscuous mode
[181760.923671] br-lan: port 3(wlan0) entered blocking state
[181760.929192] br-lan: port 3(wlan0) entered forwarding state
[181761.328116] br-lan: port 3(wlan0) entered disabled state
[181769.453920] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[181769.460673] br-lan: port 3(wlan0) entered blocking state
[181769.466158] br-lan: port 3(wlan0) entered forwarding state

I have this problem as well with my Meraki MR18, tried 19.07.3 linked here: https://openwrt.org/toh/meraki/mr18 and the 2.4 GHz radio seems unstable - stops working after several days until restarted.

I even went back to the original firmware that I had been running for years between reboots: https://github.com/riptidewave93/Openwrt-MR18/releases/tag/1.0-Final and it is unstable on that now as well (yes I wiped it without keeping the config)!

Has the 19.07.x firmware permanently altered the 2.4 GHz radio on this device to make it unstable? Does anyone have a Meraki MR18 running stably now, and if so which firmware are you using?

Same here with TP-Link TR-WR1043ND and TP-Link TL-WDR3600 with 19.07.7 version. 2.4 GHz radio stops working after several days. 5GHz has no problem at all. To fix this I even don't need to restart the router I just restart the 2.4 GHz radio only on the Wi-Fi page.

Any progress?