Sometimes things don't seem to make much sense. I'm no min-maxer and the way this game calculates its stats is still mostly a mystery to me. But I've noticed that equipping a random staff on one of my stam characters (it was either lightning or frost, but not a vMA one) made his health go up for some reason. I have never managed to understand why. There's nothing that would even suggest this. No passives, no enchantment, nothing. ZOS' code works in mysterious ways.
before slotting skills I have 2285 spell dmg and after slotting 4 sorc skills it comes out to 2391. Only 106 gained from slotting 4 sorc skills. Is this correct or is there something wrong?
Assuming you have rank 2 of expert mage and 2285 is your unbuffed spell damage you should have 2467 spell damage after slotting 4 Sorcerer skills (+8%, 1.08 * 2285 = 2467).
If not try unequipping all items/skills, log out and back in and see if that fixes things (sometimes there is a display issue with stats). If not try listing all your spell damage sources here or create a build with our build editor to see if we can track down the discrepancy.
I believe there is something wrong with the expert mage skill I am only getting about half the bonus and I have it at rank 2. @ZOS_GinaBruno Please check this.
If this is really a bug you are going to need more evidence in order to get the devs attention. 99% of the time when this sort of thing happens the player is merely "forgetting" about something which explains it or there has been a change in the stat calculations that explains it.
What I would do is:
Get naked (your character..;) and clear skills
Log out and back in
Equip one weapon
Take a screenshot of your stats
Slot one sorc skill and take a screenshot
Repeat as needed until the issue is obvious (or until you can't find it)
Post screenshots here first and if a bug is found make a complete post in the Bug forum (this forum gets noisy and things are easily overlooked).
Honestly, this applies to just about *any* bug you think you've found in the game. Either the above process will reveal it isn't actually a bug or in the rare case actually give the devs enough information to actually verify and do something about it. There are probably 100s of posts each day that just say "X is broken" and dev can't spend their time trying to figure out and verify most/all of them.