Galaxy S6 :: 5.1.1 - Key Strokes Randomly Not Registering?

I am on my 3rd replacement phone now because of this issue and just figured out why it is happening. everytime i get a replacement and update it from 5.0.2 to 5.1.1 is starts missing key strokes.. My current replacement i purposely didnt update and it works absolutely perfectly. I have tested 4 phones now and all of them have the same exact issue. I believe the reason most people dont realize it is because of word prediction. most of the time Word Prediction will put the correct word in even tho it misses keystroke. My brother has an s6 and he didnt even realize it till i had him test it like i tested mine. I did notice it tho and got really annoyed by it and started returning phones until i realized that they all had the same issue.. Worked perfectly on 5.0.2, but as soon as i updated to 5.1.1 they started missing keystrokes.

This is how i tested and proofed to Verizon that my phone was not working right:

disable "word prediction" in the samsung keyboard settings.

in the texting app type the first row of keys and press enter repeatedly so it looks like this:

qwertyuiop
qwertyuiop
qwertyuiop
qwertyuiop

repeat about 10 to 20 times. If your phone has the same issues as all my replacements you should see missed keys 2 to 5 times in your repeated words

Example:
qwertyuiop
qwetyuiop (missed the r)
qwertyuiop
qwertuiop (missed the y)
qwertyuiop
qwertyuiop
wertyuip (missed the q and o)
qwertyuiop