Doing battle in ancient ruins for the alchemy spell quest with my sovereign, 4 air shrills to defeat.
Before battle: Level 4 with 71/96 exp
after battle (autoresolve): Level 5 with 30/125 exp
after battle (tactical combat): Level 5 with 68/125 exp
after battle (passing 1 turn, then autoresolve): Level 5 with 68/125 exp
basically if you want full exp but not the tactical battle skip one turn and then autoresolve instead of autoresolve only, which is, i think, a bug.