B650 Steel Legend - RAM Timing settings ignored

I have built a machine based on the following components-

Motherboard: B650 Steel Legend WiFi (Bios 3.16 upgraded to 3.20)
CPU: AMD Ryzen 7 7700
RAM: Crucial Vengeance 32GB (2x16GB) DDR5 6000MT/s CL30

While doing intial testing and tuning of the system I have discovered a weird problem- the memory speed and timing settings in the BIOS seem to have no effect

Symptoms
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I can set the RAM speed and timing either by loading the EXPO settings from the RAM, or manually, to 6000 MT/s with timings of 30:36:36:76 (the spec of the RAM).

The settings show correctly in the BIOS, and persist across reboots. The system POSTs (after the normal RAM tuning delay) and runs normally HOWEVER

Running HWiNFO64 shows that the speed+timings actually in effect are still stuck at the defaults of 4800@40:40:40:77 ?!

The develoipers of HWiNFO have confirmed that it reads the RAM timings directly from the controller on the motherboard, so the default timings are the ones that are being used, even though the BIOS says otherwise.

While I do at least have a working system, having paid for decently fast RAM i'd like to be able to get the benefit from it.

This is a pretty weird problem. Has anyone else seen anything similar?