I have the Joann's app too. Get on their mailing list if you aren't already...I have gone in with paper coupons from the flyer, plus printed coupons from email, PLUS coupons from the app and they let me use them all on the same purchase.
There aren't any Hobby Lobbys in my area, but there are Beverly's fabrics here, and they will take Joann's coupons but only honor them up to 30% off. (So you can use a 50% off coupon, but they'll only give a 30% discount for it.) They don't even have signs that say this; another local quilter on this forum clued me in!