Targeting issues unknown if its mouse

Ok lately I have been noticing more on my lock than any other toon that at points expecially when my hand is not on mouse that my target seems to switch makes me leary of actually dropping my spells when in raids cause it will switch regardless I have went through my system many times to check mouse settings and such to no luck of finding the issue any help will be grateful
i can honestly say i'm having the same issues! this is my first time healing and first time running dungeons, and i am always targeting my tank, but at RANDOM i will no longer be targeting anything, a random mob, or another player! my heals are going to waste and i'm having to quickly play catch up heals with the tank! sometimes i even lose them. :c its getting very frustrating, very disconcerting, and it only seems to be my healer.

i don't know if this is an addon issue, but i have tried to disable all of them and it still doesn't help. i'd seriously like to know how this is happening. anyone have any idea's or similar effects?
I'm having this issue too. I FINALLY figured out that it's happening when I hold the right mouse button down and move (for view) it will target on any nearby friendly targets. Also will target whatever the cursor is touching when I let go of the rt. mouse button. REALLY annoying and targeting in raid is MISERABLE! I'm guessing it's a bug with windows 10? I couldn't find any helpful settings in game either. When you hold and move to view your cursor should disappear right??? The severity of the issue seems to vary...which is odd too.

I also tried taking off addons etc. nothing has worked. It's annoying casting and realizing you dropped target AGAIN...not good.

Maybe should re install the game?
Bump. This has been happening frequently in BFA, didn't have this problem at all in Legion. Seems to be associated with holding right click to move camera. Target focus will randomly drop or switch to different target or ally. Really kills my DPS and makes me apprehensive to drop spells, as it might pull some other mob in M+.

All the blue posts I've seen regarding this issue are quick to blame the user mouse. I can confidently say it's not my mouse, as it's happening to a friend as well, and we both have brand-new, expensive gaming mice.
Don't necro a 3 year old post. Start a new one with your issue.