Many times I faced a situation where a Wireless client didn’t support some of the features that I configured for the WLAN, hence I needed to look for what exactly wasn’t supported and trying to workaround it. It would help a lot if Router OS had a capability Profiler on WLANPI (https://github.com/WLAN-Pi/wlanpi-profiler) where it could act as an AP and capture details from the Association Request frames of all the clients that would try to connect.
It doesn’t seem like it is possible to get to these frames in RouterOS as the moment you enable sniffing on the interface, it stops being an AP and the separate packet sniffer tool can’t capture these frames either.