A few days ago I had a 12 string to work on. It was a black acoustic Fender made in Korea (can't remember the model). Made bone nut and saddle, changed a broken tuner and other minor electronics problems. I put on a set of 0.12. Next day the bridge had lifted (not completely, just a bit). I re-glued the bridge but added a rivet (with a washer inside) hidden by a faux mop dot. I tuned the guitar a whole step down. Should have I been more confident and tune it to regular pitch? How do you manage with 12 strings? My Yamaha has the same strings and never had problems at the bridge (just a normal belly on top). I must say I usually use it on open tunings.
Again, Merry Christmas and Happy New Year to everybody, especially to Frank who let us do what we do here.