A little similar to Buffer size blocked with Asio drivers but I think deserves some extra attention.
Using a 204HD, I experienced issues where the advertised buffer size in Ardour does not correspond to the buffer size as indicated in the ASIO control panel. Which to believe? Also, when selecting 64 samples in Ardour AND the control panel (even set it before opening Ardour), the buffer size switches to 128 samples in the control panel. Very strange.
Using a UR44, I experienced the same issues as in the linked topic where the buffer size cannot be changed even after the Yamaha driver control panel buffer size has been updated. I had to completely restart Ardour to be able to use the new setting. Compared with all other Windows DAWs I used that manage to switch on the fly, this is a little annoying, I suppose.
All this said, I’m a Linux user but installed Ardour 6.3 on Win10 to see what the experience would be like for some students of mine who are thinking of moving to Ardour/Mixbus on that OS. Everything else seems fantastic I have to say (and I assume based on git commits that VST3 is to follow shortly).