I've had this issue on any vanilla private server I've tried but never on any other game or retail WoW. To move (forward,left,right) I mostly hold both mouse buttons down. To strafe I hold right click and use the keyboard. The problem I have only occurs in combat specifically when using abilities and it makes PVP damn near impossible for me. My mouse often "locks-up", for example; I start combat with charge as a warrior and immediately after the ability completes I try to run and turn left by pressing both mouse buttons down, but instead of turning left my character will just run forward until I release the left mouse button and reclick it. I know it's the left click that's the issue because I can release the right mouse button and keep retrying to turn left/right but it is futile, I just run forward as long as I keep holding down the original left click.
It happens mid-fight as well, where I'll use an ability and move at the same time and it'll lock up on the first attempt causing me to just run forward and have to release my mouse and click both buttons again. This just ends up in me doing squares in pvp instead of circles around my opponent because the initial press locks me into just moving forward...
Does anybody else have this bloody issue and can it be fixed? I'm sick of getting ganked by people because I can't do something as simple as run properly, I must look like a spastic when it's happening.
Using W for forward instead of both mouse buttons causes 0 issues, but I much prefer having my left hand free for my keybinds.
TL;DR: My left click is locking my mouse up in combat, making me unable to move left/right when pressing both mouse buttons.