Lg stylo2 moving apps to sd card problem
According to this it was a feature removed in Marshmallow update.
Quoting user tommytm75 from the android central forum:

There is no solution yet. I have the same issue. After going back and
forth with LG, finally someone answered my question.  This is the last
email I got from LG.
Hi Tom,
Thank you for contacting LG!
We regret any inconvenience you’re having.  Upon checking, I’m afraid
that the Adoptable Storage feature  has been removed on the
Marshmallow update of the LG G Stylo  and this means you may not be
able to fully use the SD card as internal storage of the device. I’m
so sorry to disappoint you in this matter.
Should you have any other questions,  please feel free to contact us
again via Email, Live Chat, or Phone by calling 1-800-793-8896.
Thank you and we wish you all the best.
Sincerely,
Edrian
--- LG Customer Service

Source: LG G STYLO - not enough memory on sd card?