It only appears that nothing is happening because you are using Bars & Beats as your only timescale - 2 bars at 50 BPM is still 2 bars at 60 BMP, even though one takes longer to play than the other. If you added a second ruler Track and set it to Minutes & Seconds, you’d easily see things changing. A project isn’t in Bars and Beats OR Minutes and Seconds - both are always in effect, although we can choose how we want to view it by changing the Ruler scales.
Preferences settings.
Here’s a rundown about how Bars & Beats interact with Minutes & Seconds for Audio. The info about Timebase applies equally to Audio & MIDI. But the stuff on Musical Mode only applies to Audio and not MIDI