35 years ago when sequencers first came out, they ALL could do 12/8, 6/8, etc. correctly. Fast forward 35 years and the ONLY DAWs that can do this correctly today are Performer and Pro Tools.
You have 4 solutions, (1) only write in 4/4 and 3/4 (unacceptable), (2) Play in 4/4 with "triplets" (totally unacceptable), (3) do mathematical equations to get your "tempo" to come out right, by using the tempo you want, divided by 2 multiplied by 3 (guaranteed to create a botch using this method and again, totally unacceptable), (4) go with a pro level DAW... get Digital Performer.
DP does this correctly, and has been doing so since day one back in 1985 (as well as most every other DAW back then, including Voyetra which ran under DOS!!!).
In DP, you can set your click to anything, and also tell it how you want it to click. Meaning, if in 4/4, you can tell it to click every 8th note if you like. 12/8 is a breeze. Just enter 12/8, then set the click base to a dotted quarter. Presto! You're clicking on beats 1,4,7,10.
I really like Studio One, BUT... this tempo setting thing is a deal breaker. Was hopeful, but I need a professional level DAW with the type of projects I seem to get.