WAX630 - 2.4ghz radio only SSID, constant client disconnects or undiscoverable wifi/SSID

I have set up a new WAX630 access point (firmware V9.6.3.2) to replace the wireless portion of my existing wifi/router setup (Asus RT-AC3200 using custom Tomato firmware but will eventually be replaced by a HP T740 client running PfSense). This AP is in use in a single-floor, home < 1500 sq ft.

Without otherwise changing the default settings of the WAX630 access point (I've rebooted/reset to factory settings a few times to make sure there weren't configuration errors), I created two SSIDs:

1. The first SSID will be my main one and uses both radios 2.4ghz and 5ghz (hi/low) radios (WPA3/2). I have not seem to have any issues when connecting to this SSID

2. The second SSID; I want to use it for my smart home and IoT devices and i will eventually segregate them on their own VLAN/subnet. However, when this SSID is set to use only the 2.4ghz radio, I have constant client disconnects and often the SSID is not discoverable by clients. Somehow, these connection issues more or less resolve when I enable the 5ghz radio as well. The clients on this network include about two dozen various devices: cameras, Google Home devices, Amazon Alexa hub, smart plugs, etc. Some of these devices support 5ghz wifi although the majority only support 2.4ghz wifi. As these devices don't require much bandwidth, I'd like to isolate them to just the 2.4ghz band/radio. Using a wifi analyzer app on my Pixel 6, I have selected a 2.4ghz channel (6) with minimal interference from nearby neighbors' AP's. I had been previously using those same devices on my ASUS RT-AC3200 connected to only the 2.4ghz radio without any issues. I'm kind of at a loss as to why all these issues arise when I only enable the 2.4ghz used for this SSID on the WAX630 AP.

Any help would be much appreciated.

Thanks.