Reference value for bpm....only quarter?

In Cubase the bpm seem to refer only to the quarter notes. If I set a speed of 50 bpm in 4/4, the eighths have a speed of 100 bpm. While if I set a speed of 50 bpm in 12/8, the eighth notes have a speed of 150 bpm. If in Cubase I change the metric from 4/4 to 12/8 (or, for example, from 1/4 to 3/8), the graphic division changes, but the speed remains the same. Apparently, there is no way to tell bpm to refer to a value other than quarter note. If there is a way, I have not found it. So every time I have to calculate the speed to get the desired result. I need to set a speed of 100 bpm to dotted quarter notes. To achieve this, I have to set a speed of 150 bpm. Whenever I have to use compound time I have to do this. So there is no way to change the bpm reference value? I tried with the click patterns editor, but this only affects the metronome clicks, not the speed. Can someone help me?
Thanks so much.

Yes this is a problem, the tempo value in the transport is locked to quarters.

For calculating you can open the Score Editor and use the tempo indicator which can be set for different rhythm values, see gifs attached. It’s bass ackwards, but it’s a work-around.
insert Score tempoIndicator.gif
MM in Score.gif