I have this set of right hand open string exercises for classical guitar. Many are in 4/4 but some are in 6/8 (see pic below). The notes are grouped in 6 but there is no tuple notation. Reading as straight 6/8 I expect 12 16th notes per measure. Lines 1 and 2 show 24 16th notes per measure. My question is am I reading it wrong or is there a missing bar in each line separating each into 2 groups of 12 16th notes. Thanks.
It's incorrect. Either it's in 12/8, or there's a barline missing, or they should be demi-semiquavers.
It's definitely a typo. You can tell by the lowest voice which always has a dotted quarter note per group of 16th notes. As currently written, it is in 12/8 . It could be in 6/8 if the bar line was instead after every two groups.